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A Power Outage for Prostate Cancer

Limiting Prostate Cancer’s Fuel by Restricting Calories and Changing the Diet:  Just when it seems like the picture of diet and prostate cancer is finally coming into focus, Nicole Simone, M.D., a radiation oncologist at Thomas Jefferson University, has added a new dimension.  It may not be just a question of the good foods you do eat, and the bad foods you don’t eat:  It also appears to matter, very strongly, how much you eat at all.

Simone’s research in prostate cancer and also in breast cancer suggests that restricting calories has many anti-cancer effects in the body – including, in mice, decreasing the likelihood of metastasis.  Early research in humans has shown, so far, that it lowers inflammation, changes the gut microbiome, may decrease the side effects of systemic therapy and generally seems to slow down cancer.  In effect, caloric restriction gives cancer a “brown-out,” limiting its energy.  “We’re just beginning to understand the promise and the power of caloric restriction,” says medical oncologist and molecular biologist Jonathan Simons, M.D., CEO of the Prostate Cancer Foundation (PCF), which funded this research.  “If there were a drug that could do all these things, we’d prescribe it in a heartbeat.”

Wait… aren’t people with cancer supposed to keep their calories up?  If you’re thinking that limiting calories when someone’s fighting cancer seems like the opposite of the common wisdom – well, you’re right!  “This is not what we were all taught in medical school,” says Simone.  And she’s not entirely sure why this approach produces as many good effects as it does – but here’s a clue:  One way to look for various forms of cancer is with a PET scan, which involves injecting a radioactive dye.  “That dye is actually a radio-labeled glucose,” which is eagerly taken up by tumor cells because “cancer loves to eat.  Cancer is metabolically active, and sugar is one of its favorite foods!”

Simone’s laboratory has been investigating caloric restriction for several years.  “Initially, we were looking for a way to increase the effectiveness of radiation and chemotherapy in tumors that have a poor response to standard therapies.”  In mouse models of hormone-sensitive breast cancer, Simone found that simply restricting the mice’s daily caloric intake made a big difference:  it not only altered cell metabolism and made cancer cells more vulnerable to radiation and chemotherapy.  It also “decreased metastasis and increased overall survival.”

If this worked in breast cancer, would it work in prostate cancer?  Yes!  “In several models of hormone-sensitive prostate cancer, we found the same,” she says.  “We were able to decrease tumor growth, decrease metastasis, and increase survival.”  Then Simone’s lab tested caloric restriction in mice with castrate-resistant prostate cancer (CRPC), cancer that is no longer controlled by androgen deprivation therapy (ADT).  Again, caloric restriction affected how tumors responded to radiation.  “We saw some really interesting systemic, molecular changes,” Simone says.  “We wanted to take it a step further, and use that preliminary data as a launching pad to see what would happen in patients with prostate cancer if we put them on a caloric restriction diet.”

Eating 25 percent less:  In a pilot study, 20 patients – men diagnosed with localized prostate cancer who were scheduled to have prostatectomy – underwent caloric restriction for 21 days.  Simone individually tailored each man’s daily calorie total, based on what he had reported eating for several days ahead of time.  “We figured out their average caloric intake and then decreased that by 25 percent.”  Simone’s team also gave the men some dietary guidelines, encouraging (but not requiring) an anti-inflammatory diet with less refined sugar and processed food, more fruits, vegetables and complex carbohydrates.  “The men were able to stick to the diets really nicely,” she says.  “We went over their diet logs and calculated their dietary inflammatory index.   They did increase their anti-inflammatory foods!  They also lost an average of 12 pounds each.”

Could just three weeks of restricted-calorie, pretty much anti-inflammatory diet make a difference?  Yes, in several ways:

A decrease in systemic inflammation.  Men had changes in inflammatory markers in the blood, including a lower sedimentation rate (a blood test that measures inflammation).

Changes in the gut microbiome.  Rectal swabs, taken before the men started the diet and three weeks later, were sent to PCF-funded investigator Karen Sfanos, Ph.D., at Johns Hopkins, who performed in-depth analysis.  In the swabs taken at three weeks, Sfanos found a significant change in what the gut microbes were producing:  more butyrate!  Butyrate is an important fatty acid that helps control inflammation and is made by beneficial bacteria.  The fact that butyrate increased suggests that the population of bacteria in the gut changed for the better, simply with caloric restriction and an anti-inflammatory diet.

Less inflammation in the gut wall, as measured by lipopolysaccharides (LPS) in the blood.  “When there is inflammation in the gut, it creates spaces between the epithelial cells in the gut wall.”  Inflammatory cells can “leak” out of the gut into the blood, and increase inflammation elsewhere.

Less inflammation in the tumor.  “We saw a decrease in inflammatory markers such as NF-κB (an inflammatory pathway) in the tumor itself, and in MIR21.”  MIR21 is a microRNA gene (which makes RNA instead of proteins) that is believed to drive cancer development, growth, metastasis, and resistance to treatments.  Simone is discussing this aspect with another scientist she met at PCF’s Scientific Retreat, Shawn Lupold, Ph.D., of Johns Hopkins, who is a pioneer in the study of MIR21.

Ultimately, Simone believes, caloric restriction can play an important role for men with all stages of prostate cancer – but to make it even more effective will also require precision nutrition, based on precision oncology.  In this case, that means figuring out whether someone’s cancer prefers a diet that is sweet or savory.  “Prostate cancer can metabolize through the glucose pathway, or through lipid pathways,” says Simone.  Understanding which pathway really appeals to a particular cancer – some prefer sugar, some really go for fat– “can tell us how your cancer is driving its own energy.”

Thus, “if the tumor’s feeding on lipids, we change the dial on fat content in the diet.”  And if the tumor prefers sugar, then a diet aimed at keeping sweets and simple carbohydrates to a minimum will foil the cancer’s gustatory pleasure.

One of the biggest challenges with chemotherapy, ADT, or even radiation therapy, is resistance to treatment:  the cancer evolves to minimize the damage of attempts to kill it.  “Diet can almost be a more powerful tool,” says Simone.  “Cancers get smarter; a drug will work well for a while, then all of a sudden, cancer will figure out a way around it.  The power of restricting food is that it provides less energy for the cancer to use up.”

In addition to the book, I have written much more about prostate cancer on the Prostate Cancer Foundation’s website, pcf.org. The stories I’ve written are under the categories, “Understanding Prostate Cancer,” and “For Patients.”  As Patrick Walsh and I have said for years in our books, Knowledge is power: Saving your life may start with you going to the doctor, and knowing the right questions to ask. I hope all men will put prostate cancer on their radar. Get a baseline PSA blood test in your early 40s, and if you are of African descent, or if cancer and/or prostate cancer runs in your family, you need to be screened regularly for the disease. Many doctors don’t do this, so it’s up to you to ask for it.

 ©Janet Farrar Worthington

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Worried About Prostate Cancer?  Be Proactive! Part One

Part One:  Live Your Best Life!

What can you do to live your best life?  You might say, quite reasonably, that your best life does not include prostate cancer.  True.  But no matter where you are in your journey – prevention, treatment, recovery, or survivorship – what can you do to maximize the good, to help your physical and mental wellbeing?  There’s actually quite a lot!

For example: Exercise not only helps you lose weight; it helps fight depression, and it even can help slow down prostate cancer!  And eating the right diet – as opposed to eating a lot of junk and chemicals – can boost your spirits, your energy level, and just generally make you feel better.  Even better:  it can help lower inflammation and insulin, and this can help your body fight prostate cancer, and can help prevent diabetes, cardiovascular disease, and other chronic illnesses.

There is growing evidence that the lifestyle choices that help prevent or fight other diseases – like, eating low sugar for diabetes, or exercising for your heart – can also help prevent or slow down prostate cancer.

Here are three basic principles:

What lowers inflammation helps fight prostate cancer.

What fights diabetes and insulin resistance helps fight prostate cancer.

What is good for the heart is good for the prostate.  We will cover all of this here and in part two.

Studying Diet is Hard

For the Prostate Cancer Foundation (PCF), I interviewed two scientists who study lifestyle factors and their effect on prostate cancer:  Epidemiologist June Chan, Sc.D., of UCSF, and epidemiologist Lorelei Mucci, M.P.H., Sc.D., of Harvard.

Right off the bat, both of these experts note that studying food is hard, and the answer to staying healthier is not one single thing.  There is no dietary magic bullet, and if you see one advertised and choose to take it, do so with a huge proverbial grain of salt!  In many studies over the years, scientists have tried to isolate specific foods to see if they promote or prevent cancer – but they did it by asking people to recall what they ate over certain periods of time.  And most people don’t have ideal memories:  “Yes, I ate that fairly regularly.  No, I didn’t eat this – wait, maybe I did.”  See the difficulty?

Okay, so what if people keep a food journal?  That’s more helpful, although these kinds of studies, done right, take many years.  Even then, if you isolate certain foods that seem promising, you still don’t know exactly what’s happening!  Let’s say you are studying what people eat and you notice a trend in those who didn’t get cancer:  they eat apples (hypothetically).  What kind of apples?  Is it all apples, or just Granny Smiths?  Were they all grown in the same type of soil?  Were they cooked, or eaten raw?  Peeled or not?  Organic or not?  How many did people eat a day?

But wait!  Did these people even have an actual benefit from eating the apple – say, one they brought to work from home – or did they benefit from not eating a bag of cheese puffs or Twinkies from the vending machine instead?

And wait some more!  Do the people who benefited have genetic or molecular differences that make them more likely to be helped by apples?  Or… are people who eat apples also more likely to exercise and take better care of their health in general – so maybe it’s not even the apples but their whole lifestyle that made the difference, and we’re back to the drawing board!

This is why science around nutrition takes time.  Remember back in 2010 when coffee was bad?  And now, here we are in 2020 and coffee is good?  This stuff evolves.  The good news is, we’ve learned a lot.

Broad Strokes are Better

Scientists don’t have a Paint-by-Number approach to food science, with every single food accounted for.  But they are able to paint with broad, but definitive, strokes.

In our interviews, June Chan and Lorelei Mucci both cited work led by Harvard scientists Fred Tabung, Ph.D., M.S.P.H., and Edward Giovannucci, M.D., Sc.D., that look at the relationship between diet and inflammation.  In one, the scientists tracked inflammatory markers in the blood and whether inflammation was raised or lowered by what people ate, based on data from thousands of participants in the Nurses’ Health Study and the Health Professionals Follow-Up Study.  The key for us is the foods they found that reduce inflammation:  dark yellow vegetables (carrots, winter squash, sweet potatoes, etc.); leafy green vegetables (like spinach, broccoli, kale, etc.), coffee, and wine.  Beer (one bottle, glass, or can) was in this category, too.  So was tea, but its effect was not very strong.

The pro-inflammatory (bad) category, included processed meats (hot dogs, bacon, pepperoni, lunch meat, etc.), red meat, refined grains, high-energy beverages (with additives and sweeteners), and “other vegetables,” like potatoes and corn.  Interestingly, not all fish is equal:  canned tuna, shrimp, lobster, scallops, and “other” fish were more inflammatory than “dark-meat” fish like salmon or red snapper.

But if you love canned tuna, and if you love a baked potato or corn on the cob, don’t freak out:  remember, broad strokes!  The key seems to be to make sure you do eat the anti-inflammatory foods.  For example, the anti-inflammatory effects of leafy green vegetables, dark yellow vegetables, wine and coffee are more powerful than the very mild, pro-inflammatory effect of “other fish” or “other vegetables.”  If you feel that you just can’t give up meat entirely, that’s okay – just aim for smaller portions of meat, surrounded by anti-inflammatory vegetables.  Example:  instead of regular fries, try sweet potato fries.  They’re really good, and they fight inflammation!  You can have your burger, but still help counteract inflammation:  it’s a win-win!

So:  what about foods that are bad for diabetes and insulin resistance?  Tabung and Giovannucci led another study, also using data from the thousands of participants in the Nurses’ Health Study and Health Professionals Follow-Up Study, to assess the “insulinemic potential” of diet and lifestyle – basically, how foods and exercise affect blood sugar and insulin resistance, as measured by certain biomarkers in the blood.  Foods that did not raise blood sugar or insulin resistance included wine, coffee, whole fruit, high-fat dairy (whole milk, sour cream, a half-cup of ice cream, a slice of cheese, etc.), nuts, and leafy green vegetables.  Physical activity was also good for lowering insulin resistance and blood sugar.

What do the experts make of this?  Benjamin Fu, a postdoctoral fellow in Lorelei Mucci’s lab at Harvard has been looking at these two different dietary patterns: “a diet associated with hyperinsulinemia, and a hyper-inflammation diet.”  The two diets have some overlaps, but are not identical.  Neither is good for men worried about prostate cancer, Mucci says, “particularly the hyper-insulinemia (blood sugar-raising) diet, which is associated with a 60-percent risk of more advanced or fatal prostate cancers.”  Let’s just let that sink in for a second:  if you eat a lot of carbs and sugar and you get prostate cancer, you’re more likely to have a serious form that could kill you.  Okay, let’s go on:

Mucci continues:  “The hyper-inflammatory diet also is associated with an increased risk of prostate cancer,” particularly in men who develop cancer at a younger age, in their forties and fifties.  “It may be that earlier-onset cancers are more susceptible to the effect of diet and lifestyle.”

What does heart health have to do with it?  A lot, for many reasons.  It turns out, says Mucci, that “cardiovascular disease and other chronic diseases are the major cause of death in many men who have prostate cancer.  If you look at men with localized prostate cancer and survival outcomes over 10 years, three-fourths of the deaths in those men will be due either to cardiovascular disease or another chronic disease.  Only one-fourth of the mortality is due to prostate cancer.”  Now, you may be thinking, we all have to die of something, right?  This is true, but “these men are dying sooner than they should, and eating a plant-based diet rich in cruciferous vegetables will help lower that risk of cardiovascular disease.”

Which brings us to the Mediterranean Diet:  Not only do people in Mediterranean countries, as compared to Americans, eat more vegetables and fruits, fewer fatty foods, less processed junk, and less red meat – “which increases insulin resistance, increases inflammation, raises cardiovascular risk and also is part of a dietary pattern that may increase obesity, as well,” as Mucci notes.  You know what else they eat a lot of?  Olive oil.  Greater than 30 ml a day, which is a little over two tablespoons.  “There’s really good evidence that extra virgin olive oil (EVOO), either on its own or as part of the Mediterranean diet, substantially lowers the risk of cardiovascular disease and lowers the risk of overall mortality.  The evidence specifically for men with prostate cancer is much more limited, but given the strong benefits for overall death and cardiovascular death in particular, not only using EVOO, but using it to replace butter or margarine, is something that is worth doing.”

 

Coming up:  Part 2:  What’s Good for the Prostate is Good for All of You!


In addition to the book, I have written much more about prostate cancer on the Prostate Cancer Foundation’s website, pcf.org. The stories I’ve written are under the categories, “Understanding Prostate Cancer,” and “For Patients.”  As Patrick Walsh and I have said for years in our books, Knowledge is power: Saving your life may start with you going to the doctor, and knowing the right questions to ask. I hope all men will put prostate cancer on their radar. Get a baseline PSA blood test in your early 40s, and if you are of African descent, or if cancer and/or prostate cancer runs in your family, you need to be screened regularly for the disease. Many doctors don’t do this, so it’s up to you to ask for it.

 

 ©Janet Farrar Worthington

 

 

 

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Could Anti-Inflammatory Drugs Work Against Prostate Cancer?

If, as we have seen, inflammation can lead to prostate cancer, could anti-inflammatory agents help protect against it?

The jury’s still out.  However:  Johns Hopkins epidemiologist Elizabeth Platz, Sc.D., has been intrigued by this possibility for many years.  She is senior author of a new study on the use of aspirin and statins, published in Cancer Prevention Research.  The study, of men in the placebo arm of the Prostate Cancer Prevention Trial, doesn’t answer this question once and for all – but adds more weight to the idea that, for lowering the risk of developing potentially fatal prostate cancer, fighting inflammation is a good thing.

Evidence from observational studies has suggested that when taken regularly over time, aspirin may lower the risk of prostate cancer.  These drugs block enzymes that play a key role in the body’s inflammatory response.  Other studies have linked long-term use of statins, prescription drugs that are used to lower cholesterol but that also are anti-inflammatory, to a lower risk of advanced and metastatic prostate cancer.

In this most recent study, the investigators looked for inflammation markers in benign prostate tissue samples.  “We compared the use aspirin and statins with the presence and extent of inflammation in the prostate tissue,” says Platz.  They also looked at prostate biopsy slides for the presence of certain immune cells that are involved in inflammation.

“Of 357 men, 61 percent reported aspirin use, and 32 percent reported statin use,” Platz continues.  “Aspirin users were more likely to have low FoxP3, a T regulatory cell marker, and statin users were more likely to have a low CD68, a macrophage marker.”  “Our results suggest these medications may alter the immune environment of the prostate. A next step is to determine whether these immune alterations may underlie the epidemiologic observations that taking an aspirin or statin may protect against getting advanced prostate cancer, and dying from it.”

Prostate Cancer Loves Fats          

Here’s some more recent research out of Johns Hopkins, a neat bit of  basic science that may help explain the findings of Platz’s recent study:  “Our work is mechanistic,” says investigator Marikki Laiho, M.D., Ph.D., director of the Division of Molecular Radiation Sciences, “and provides insight into how the tumor microenvironment senses the excess load of the lipids.  Diet and statins obviously relate to the amount and regulation of the lipids, and have shown those clear correlations to prostate cancer.  However, we need to understand why to be able to correct the problem. Our work provides at least one explanation how the lipids fuel cancer. One part of the work was just to feed the prostate cancer cells with cholesterol, which made them more invasive.”

It turns out that even on a cellular level, prostate cancer gravitates to its own kind of junk food – the tiny version of deep-fried Oreos with a side of chili cheese fries.  Laiho and colleagues have just figured out how the body enables prostate cancer’s terrible diet.

The culprit is a lipid-regulating protein called CAVIN1, the scientists reported in the journal, Molecular Cancer Research.  In lab studies, when CAVIN1 was removed from cells in and around the prostate tumor, the fatty acid that was in those cells spilled into the tumor’s microenvironment.   The effect on prostate cancer cells was dramatic:  the cancer cells soaked up the lipids, which then acted as turbo fuel to make the cancer spread more aggressively.

“In every prostate cancer cell line we tested,” says research fellow Jin-Yih Low, Ph.D., the study’s first author, “tumor cells universally had an appetite for the lipids, using them to strengthen the protective membrane around the cell, synthesize proteins and make testosterone to support and fuel the cancer’s growth.  The tumor cells then behaved more aggressively, exhibiting invasive and metastatic behavior.  Just having access to the lipids gave the tumor cells more power; the tumor’s behavior changed.”

But wait!  There’s more:  nearby cells changed, too.  Deprived of their lipids, normal stromal cells started to churn out inflammatory molecules, adding fuel of their own to the fire. 

Laiho’s team then confirmed their findings in mouse models, comparing tumors with and without CAVIN1 in the stromal cells.  In the mice, Laiho says, “although the presence or absence of CAVIN1 did not affect the speed of tumor growth, lack of CAVIN1 definitely caused the cancer to spread.  All of the mice with tumors that lacked CAVIN1 had a twofold to fivefold increase in metastasis.  The tumors also had a fortyfold to hundredfold increase in lipids and inflammatory cells.”

The investigators were surprised at these results, Laiho adds.  “We suspected CAVIN1 was important, but we didn’t realize how important.  The tumor’s microenvironment matters, and the amount of lipids matters a lot.”  Just changing the level of lipids “created a situation of rampant metastasis.”

What could come from this research?  One possibility is development of a new biomarker:  a loss of CAVIN1 in local or locally advanced cancer, for example, could signal a higher risk of metastasis.  The next step is to understand more about the inflammatory process in the tumor’s microenvironment.  “We want to understand why the inflammation brings in macrophages, immune cells that further exacerbate the inflammatory process, instead of T cells, which should attack the cancer.”  The more scientists know about how inflammation does its nasty work to inflame cancer, the closer we are to finding a way to stop it.

 

In addition to the book, I have written about this story and much more about prostate cancer on the Prostate Cancer Foundation’s website, pcf.org.  The stories I’ve written are under the categories, “Understanding Prostate Cancer,” and “For Patients.”  As Patrick Walsh and I have said for years in our books, Knowledge is power: Saving your life may start with you going to the doctor, and knowing the right questions to ask.  I hope all men will put prostate cancer on their radar. Get a baseline PSA blood test in your early 40s, and if you are of African descent, or if cancer and/or prostate cancer runs in your family, you need to be screened regularly for the disease.  Many doctors don’t do this, so it’s up to you to ask for it.

©Janet Farrar Worthington

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Infection, Inflammation, and Prostate Cancer

Why does it matter if you eat right and exercise?  Everybody knows the answer; in fact, we’ve all heard it so many times, it’s easy to tune it out:  diet and exercise are good for you.  Duh!  Who’s going to argue with that? Having a healthy lifestyle is right up there with world peace as a worthy goal!

Bear with me here:  With a topic such as this, I know I’m either preaching to the choir – people who are already exercising and eating a pretty good diet – or I run the risk of turning off the people I really want to hear this message, by seeming to preach at all: people who might think, “Go ahead, tell me what to do.  I really enjoy that.  Micromanage my life.  Maybe you’d like to come over and look at my closet and tell me what shirt to wear today.”

Okay, fine!  I’m not here to tell you what to do.  But I am going to try really hard to tell you why you might want to do certain things, and how good diet and exercise – or the lack thereof – can affect prostate cancer.

Please pardon the long set-up, but let’s begin with some facts, with plenty of links for further reading:

If you exercise, you are less likely to have cancer return after treatment, less likely to get metastatic prostate cancer and die of it.  What does exercise do?  A lot of good things for your vascular system, which, in turn, can help slow down prostate cancer metastasis.  But you know what it also does?  It helps you lose weight.

And it just so happens, men who lose weight are less likely to die of prostate cancer.

And sugar can make cancers grow faster.

And men who stop smoking are less likely to have cancer come back after treatment, and less likely to die of prostate cancer.

Exercise also helps control stress, and the stress hormone, cortisol, affects adrenal receptors, and can play a role in making cancer grow and spread faster.

Now, here’s why all this matters so much:  smoking, not exercising, quaffing sugary drinks, eating processed, fatty foods, and being overweight all contribute to inflammation.

I’m going to be writing a lot about inflammation in the next few posts, because it is becoming increasingly evident that inflammation can lead to cancer – and it’s quite possible that if we can prevent inflammation, we may prevent or at least slow down cancer.

What Inflammation Does

In a landmark study, Karen Sfanos, Ph.D., and scientists at Johns Hopkins have shown for the first time that bacterial infection can cause prostate cancer.  The study was led by Sfanos and her former graduate student, Eva Shrestha, Ph.D., in collaboration with Angelo De Marzo, M.D., Ph.D., Jonathan Coulter, Ph.D., and colleagues.  Infection? That’s not the same as inflammation!  True… but bear with me.

The bacterial culprit found in this study belongs to the family Enterobacteriaceae, which includes E. coli. Better known as a nasty gastrointestinal bug, E. coli causes inflammation in the urinary tract and is a known cause of bacterial prostatitis.  As the scientists discovered, colibactin, a genotoxin produced by some strains of E. coli, can also instigate a series of unfortunate events in the prostate.  Bacterial infection leads to acute and chronic inflammation, which can lead to the development of a lesion in the prostate called proliferative inflammatory atrophy (PIA), first described by pathologist De Marzo, oncologist William (Bill) Nelson, M.D., Ph.D., and other Johns Hopkins scientists; it can also cause DNA damage. The presence of colibactin is even more ominous, because it can directly lead to double-stranded DNA breakage. 

Sfanos suspects that this combination leads, in turn, to another development:  fusion of two genes, TMPRSS2 and ERG, that normally should remain separate, but in this case get abnormally spliced together.  Now, it may be that by themselves, TMPRSS2 and ERG are like Robert Leroy Parker and Harry Alonzo Longabaugh:  put them together, and they became Butch Cassidy and the Sundance Kid, and together, they got into much worse trouble than either one managed alone.  This TMPRSS2/ERG fusion – found in as many as half of all prostate cancers – is thought be an early event leading to the development of prostate cancer.

“We found evidence in human tissues (from prostatectomy specimens) that bacterial infections are initiating the TMPRSS2/ERG fusion,” says Sfanos.  “We don’t think this is the only way bacterial infections contribute to cause prostate cancer.  But in this particular study, the way we looked at it was by tracking the presence of these TMPRSS2/ERG fusions.”

It is entirely possible, notes De Marzo, “that other types of mutations or events could also be caused by bacterial infections or inflammation.  But looking at these fusions gave us ‘smoking gun’ evidence that bacterial infection was the initiating event.”  Sfanos adds that “the colibactin-producing bacteria, TMPRSS2/ERG fusions, PIA, and tiny buds of cancer were all there, in the same place at the same time, a snapshot of prostate cancer being born.”  The team’s early findings are available online in BioRxiv, a scientific data-sharing website, and a manuscript for publication is undergoing peer review.

Bacterial infection is a known cause of other cancers.  H. pylori, for example, is a well-established cause of stomach cancer.  “We believe that many different types of microorganisms, certain types of sexually transmitted infections (STIs), and other infections in the prostate can certainly cause the same chain of events,” says Sfanos.

How did the bacteria get into the prostate?  They could have come from the urethra.  “These bacteria are good crawlers,” Sfanos says.  De Marzo recalls what the late Don Coffey, Ph.D., the longtime director of the Brady’s scientific labs, used to say: “The urethra is like the Holland Tunnel for bacteria.”

Note:  These tiny cancers are not the cancers that were biopsied and that led to the diagnosis of prostate cancer; they’re too young even to achieve a Gleason grade.  They’re just baby sites of cancer cropping up, in addition to the more mature cancer that was already there.  Prostate cancer is multifocal:  in most men with prostate cancer, several sites of cancer develop at the same time.  But because of the unique molecular tools used in this study – looking for TMPRSS2/ERG fusions and “ERG-positive PIA” – Sfanos, De Marzo and colleagues were able to catch the formation of these invasive cancers in real time.  “This might start to explain the multifocal nature of prostate cancer,” says Sfanos. “There might be multiple infections or other inflammatory events that occur throughout a man’s lifetime.”

Sfanos suspects that the men whose tissue was used for this study “likely all had undiagnosed infections.”  These findings may lead to development of a new test, using urine or prostatic fluid, to look for colibactin or markers of inflammation in the prostate.  Future studies may look at urine samples along with prostate tissue for such markers, and  new imaging technology may one day be able to detect inflammation, as well.

For more than 20 years, De Marzo and Sfanos, with Brady scientists Bill Nelson, Srinivasan Yegnasubramanin, M.D. Ph.D., Elizabeth Platz, Sc.D., and William Isaacs, Ph.D., have studied inflammation as a risk factor for prostate cancer, particularly looking at PIA.  Sfanos “has also been the major champion of infection” as a risk factor, De Marzo says.  Now, these two paths of investigation have come together.

Could dietary changes make a difference?  “Bill Nelson showed years ago that loss of expression of the GSTP1 gene rendered prostate cells more susceptible to DNA damage caused by a chemical compound that is found in charred meat,” says De Marzo.  “Infection plus a bad diet might make this worse, and then combine that with the underlying genetics.  There might be multiple culprits, a constellation of things over years.”  We’re going to look more at diet in future posts.

Coming up next:  Could anti-inflammatory drugs help?

 

In addition to the book, I have written about this story and much more about prostate cancer on the Prostate Cancer Foundation’s website, pcf.org.  The stories I’ve written are under the categories, “Understanding Prostate Cancer,” and “For Patients.”  As Patrick Walsh and I have said for years in our books, Knowledge is power: Saving your life may start with you going to the doctor, and knowing the right questions to ask.  I hope all men will put prostate cancer on their radar. Get a baseline PSA blood test in your early 40s, and if you are of African descent, or if cancer and/or prostate cancer runs in your family, you need to be screened regularly for the disease.  Many doctors don’t do this, so it’s up to you to ask for it.

©Janet Farrar Worthington

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Metastasis Is a Spectrum

News flash:  All metastasis is not alike, and the basic category of “metastatic prostate cancer” is being redefined by doctors and scientists even as we speak.  It’s not just either-or anymore – either cancer is confined to the prostate area, or it has escaped.  It’s actually more of a spectrum, and it is very likely that there’s wiggle room – and still the potential for cure – between cancer escaping the local area around the prostate and full-blown, widespread, metastatic cancer, if we can catch it in time.

I’ve written previously about the work of Johns Hopkins radiation oncologist Phuoc Tran, because I really like what he’s trying to do:  widen the window of curability of prostate cancer.  Great news:  he’s not alone!  Doctors all over the world are rethinking metastasis in prostate cancer and other cancers, as well.  Recently, Tran was one of several experts to take part in a seminar the Prostate Cancer Foundation (PCF) put together.  I was lucky enough to be able to cover it for the PCF, and now I want to make sure you know about the kind of go-getters there are out there who don’t just accept that, if cancer leaves its primary organ, it can’t still be treated and maybe even cured with local treatment.  Better imaging is making it possible to see these cancers sooner than we ever could before.  The reason I want you to know this: if your doctor says you have a couple bits of cancer outside the prostate, so it’s time to start your lifetime of ADT – I want to encourage you to ask around and see if there’s another possibility.

Rethinking Metastasis

For a very long time, many doctors believed, and many still believe, that if we don’t cure cancer while it’s confined to the prostate, then that’s it.  Game over, it’s not curable.  Note:  That doesn’t mean it can’t be treated, sometimes for many years!   But in terms of treatment, traditionally, metastasis has meant bye-bye, local therapy, and hello, systemic therapy – androgen deprivation therapy (ADT), androgen receptor-blocking drugs such as apalutamide or enzalutamide, and chemotherapy.  For patients with metastatic prostate cancer who see their doctors every three months for just a few minutes at a time, that can feel, as one patient’s son put it, like “Lupron and a handshake.”

But a lot of things have come together recently to make doctors and scientists say, “Not so fast!  Maybe there’s a window, and maybe the window is wider than we thought.”  One of these things is the recent ORIOLE study, led by Johns Hopkins radiation oncologist and PCF-funded investigator Phuoc Tran, M.D., Ph.D.  Another is the development over the last decade of better imaging, such as PSMA-PET, which allows tiny bits of cancer to be seen months before they could be seen on conventional imaging, such as a CT scan or bone scan.   Better imaging has sparked an idea:  “If we can see it, we can treat it.”

Is it true?  Can treating little spots of cancer, before full-blown metastasis develops, prolong life?  Recently, the PCF brought together some of the country’s best and brightest – experts in radiation oncology, oncology, urology, and basic science – for a worldwide exchange of knowledge, a webinar attended by more than 300 scientists around the world.  The topic was oligometastasis.  Oligometastasis is just a little bit of metastasis; definitions vary, but generally, scientists who use this word are generally talking about fewer than 3 or 5 spots of cancer that have escaped from the main tumor.  It’s not widespread; it’s limited.  That doesn’t mean it can’t go on to cause trouble later.  If your kids or grandkids are into Pokémon, it’s like catching a little monster before it evolves into something more powerful.

Is oligometastasis treatable?  It is in some other cancers.   In colon cancer, for example, oligometastasis is treated with surgery or spot radiation in addition to removing the primary tumor, and sometimes it’s cured!   Phuoc Tran’s ORIOLE study, and now promising early results from other studies, including ORIOLE’s successor, the RAVENS study, suggest that treating oligometastasis – in Tran’s case, with SABR (stereotactic ablative body radiation, also called SRBT, a highly focused, intense dose of radiation therapy) – in addition to treating the primary prostate tumor can change the course of metastasis in some patients.

Patients reach oligometastasis in different ways.  Some reach it by biochemical recurrence – the dreaded rise of PSA after treatment of the primary tumor in the prostate with surgery or radiation.  Others are diagnosed from the get-go with cancer that has already spread outside the prostate.  The standard of care for most of these latter patients is not only not to treat the main tumor, but not to zap or surgically remove the few sites of metastasis. 

Why not?  Why the heck not?  Or, as Tran says, “It makes so much sense, so why don’t we do it?  Because we have tried periodically over the past five decades to treat metastatic disease aggressively with local therapies, and because of lack of imaging, treatment technology and just general lack of our ability to take care of patients, this approach did not work.”  In fact, he continues, “it was actually a resounding failure, and made many who lived through these periods very scared of doing much more harm than good.  One of the first texts on this concept, called ‘Solitary Metastases,’ actually started out with a chapter called “Illusion or Reality.’”

But that was then.  Even now, there’s not yet definitive proof that it works.  But take heart:  the winds of change are blowing! 

This brings us to the PCF 2020 Global Knowledge Exchange on Oligometastatic Prostate Cancer.  Eric Klein, M.D., Chairman of the Glickman Urological & Kidney Institute at the Cleveland Clinic, who moderated the discussion, set the stage with a story about a patient, seen by him and medical oncologist Howard Scher, M.D., of Memorial Sloan Kettering Cancer Center (MSKCC).  The patient was in his 50s, diagnosed with Gleason 9 cancer that extended slightly past the prostate, into the seminal vesicles.  He also had cancer in a lymph node.  The man received ADT for six months, had a radical prostatectomy, then was on abiraterone plus prednisone for a year afterward.  A bone scan showed one spot of cancer; it was treated with radiation at MSKCC.  “He’s about eight or nine years out now,” says Klein.  “He has an undetectable PSA and a normal testosterone.”

As the PCF’s CEO, Jonathan Simons, M.D., says, “One clinical case well studied can change the course of medical history.”  This patient’s exceptional clinical course has led Klein ask to the big question:  “If we can seemingly cure one man with metastatic prostate cancer, can we cure others?  And are we at a place now in the field to be asking the right questions, with the right trial behind them?”

Ralph Weichselbaum, M.D., Chair of the Department of Radiation and Cellular Oncology at the University of Chicago, is the radiation oncologist who coined the term, “oligometastasis.”  He specializes in treating it in various forms of cancer.  Not only does metastasis represent a spectrum of disease, he says, “depending on the number of metastases, the organs involved, and the pace of progression,” but patients represent a spectrum, too.  “There are subsets of patients who are potentially curable with metastasis-directed therapies” (treating breakout tumors directly, and not relying on systemic therapy alone).  What accounts for these subsets?  Genetic factors, and also the robustness of the patient’s immune system.  Weichselbaum’s research suggests that patients with a well-functioning immune system are better able to hold metastasis in check than others.  In other words, whether oligometastasis responds to treatment depends on “the complex relationship between tumor and host.”

It May Require the Proverbial Kitchen Sink

Scher and Mary-Ellen Taplin, M.D., medical oncologist and Director of Clinical Research at the Dana-Farber Cancer Institute’s Lank Center for Genitourinary Oncology, collaborated on the design of a multi-arm, multi-modality therapy clinical trial with funding from a PCF Challenge Award.  “Our focus is the patient with high-risk localized disease, or low-volume or recurrent metastatic disease,” said Taplin. The trial will be looking at many things, including potential biomarkers for sensitivity and resistance to treatment.  But one of the objectives is of particular interest:  “to eliminate all disease in patients largely incurable with any single treatment.” 

In other words: to kill prostate cancer that has escaped the prostate, these doctors and others believe, in addition to targeting the primary tumor with prostatectomy or radiation, it may well take a short course of ADT, perhaps also chemotherapy, maybe further external-beam radiation to the area around the prostate, and then radiation or radiofrequency ablation to the metastatic sites themselves.   But then, the hope is that these patients will have an undetectable PSA and that they will get their testosterone back.

There are several other important trials underway to treat oligometastasis in prostate cancer.  Of all the things scientists hope to learn from these trials, perhaps most important, says medical oncologist Ana Aparicio, M.D., of MD Anderson Cancer Center, is “how do these site-directed therapies work?”  Will the success come from messing up the circulating tumor microenvironment?  One idea is that, as cancer spreads, it sends messengers back for supplies to the other sites where cancer is already established, using the bloodstream as a liquid version of Fed Ex.  “Or, are we modulating the immune response?  Does the primary tumor have an immunosuppressive effect that limits the ability of the patient’s immune system to control the disease?  Or, are we having an immune-stimulatory effect with treatments?  We may need to build on that, and combine radiation with some novel immunotherapies.  Or, are we decreasing the tumor burden,” by zapping sites of oligometastasis?

Two Icebergs

Aparicio draws a picture for her patients to help explain:  There are two icebergs, one blue, one yellow.  “The blue one, most of it is above the water,” she notes.  “If you get rid of what you see, it is likely that the iceberg is going to take a long time to grow again and become a problem.  So, if what we see on the scans is most of the disease that’s present, then yes, addressing all the sites we can see can be beneficial.  But if it’s just the tip of the iceberg (like the yellow picture), and there’s a large burden of tumor we are not able to detect with our imaging tools, we’ll find that the disease grows very quickly.”

Better imaging, such as PSMA-PET, will undoubtedly help determine the true state of tumor burden, “particularly when the PSA is rising, but it’s less than 10; conventional imaging really is not useful when the PSA is 5 or 10,” says Phuoc Tran.  He believes the number of patients with oligometastasis in the U.S. is huge, “much higher than the number of men diagnosed each year.”  Right now, “systemic therapy is the standard of care for patients with metastatic disease,” says Tran.  “But in that gray area of biochemical recurrence (PSA creeping back up after prostatectomy or radiation of the primary tumor), as men are approaching low-volume metastasis, there’s a perfectly reasonable period in which you can ask the question, does local therapy change the metastatic process?” That was the question behind the ORIOLE trial.

“If the oligometastatic state didn’t exist, if this were not a spectrum, and if local therapy could not alter that natural history of metastasis, then we shouldn’t be able to affect progression at all with local therapy alone.  Patients should progress no matter what.  We did not see that.  Obviously, stronger evidence is needed,” but the results of the ORIOLE trial and early results of the RAVENS trial have been very encouraging.

It may be, says Weichselbaum, that we are dealing with multiple, different disease states, “requiring entirely different kinds of treatments.  We need to define really what metastasis is, and how the systemic treatments and ablative treatments fit together for optimal therapeutic outcome.”

And maybe one day, says Tran, “we can alter the natural history of metastasis, and cure these patients with formerly incurable disease.”

In addition to the book, I have written about this story and much more about prostate cancer on the Prostate Cancer Foundation’s website, pcf.org. The stories I’ve written are under the categories, “Understanding Prostate Cancer,” and “For Patients.”  As Patrick Walsh and I have said for years in our books, Knowledge is power: Saving your life may start with you going to the doctor, and knowing the right questions to ask. I hope all men will put prostate cancer on their radar. Get a baseline PSA blood test in your early 40s, and if you are of African descent, or if cancer and/or prostate cancer runs in your family, you need to be screened regularly for the disease. Many doctors don’t do this, so it’s up to you to ask for it.

 ©Janet Farrar Worthington

 

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Cancer’s Sweet Tooth

Cancer loves sugar, and sugar really loves cancer.  Isn’t that sweet?  Actually, no, it’s more like a match made in hell – because sugar (glucose) makes many types of cancer grow faster.

Scientists have long known that cancers soak up glucose like a sponge; in fact, German physiologist Otto Warburg, who found that tumors extract glucose at a rate 20 to 50 times higher than do normal cells, won the 1931 Nobel Prize for for his research on metabolism.  Lew Cantley told me that.  Cantley, Ph.D., is a world-renowned scientist and Director of the Sandra and Edward Meyer Cancer Center at Weill Cornell Medicine.  I recently interviewed him for the Prostate Cancer Foundation’s website, pcf.org.

Cantley has spent much of his career studying the interplay between sugar and cancer.  His studies suggest that it’s not so much the amount of glucose in your bloodstream that helps promote cancer, as it is the level of insulin, the hormone made by the pancreas that controls glucose.  Insulin helps turn glucose into immediate energy, and also helps your body pack it away for longer-term storage.  Briefly, when you eat, your blood sugar goes up; this causes your pancreas to say, “Hey! We need to make more insulin!”  Insulin, like Paul Revere, then travels rapidly throughout the land, telling the cells to let the glucose in, either to be used right away or saved in muscles, fat cells, and the liver.

Why does a tumor suck up more glucose?  “The main reason,” says Cantley, “is that insulin can turn on the glucose transporters (proteins on cell membranes that carry glucose into cells), similar to those in the liver, muscle and fat.  The presence of those glucose transporters on tumor cells is in part regulated by insulin.  That’s why I keep focusing on the insulin.”

Cantley began studying the insulin receptor in the 1980s, when he was on the faculty at Harvard University.  A few years later, after moving to Tufts University, he discovered an enzyme called phosphoinositide-3-kinase (PI3K); PI3K signals cells that insulin is present; the cells, in turn, open the valve that lets in sugar.  Normally, PI3K does good and vital work, helping cells survive, grow and proliferate.  But sometimes it goes awry; in Type II diabetes, this PI3K pathway becomes sluggish, cells don’t respond appropriately to insulin and become insulin-resistant.  But in cancer, even in someone who’s insulin-resistant, PI3K does its job too well; glucose floods in, tumor cells feast on sugar and grow faster.  “What we now know is that mutations in the PI3K pathway make tumor cells hyperactive in response to insulin.”

In many cancers – sugar-loving cancers; not all cancers are addicted to sugar, but many are – PI3K is like a power switch that drives growth.  “PI3K is the most frequently mutated cancer-promoting gene in humans,” says Cantley.  It may be involved in as many as 80 percent of cancers, including breast cancer, bladder cancer, and certain brain tumors.

What about prostate cancer?  Well, one of the most common genetic events in prostate cancer is the loss of a gene called PTEN; cancer just knocks this gene out.  “PTEN makes an enzyme that reverses what PI3K does.  PI3K makes a lipid, and PTEN destroys that lipid; you have to have a balance between those two enzymes to keep growth under control.  But in prostate cancer, and in breast cancer , the loss of PTEN activates production of this lipid that drives cell growth.

“This tells us we probably should try to keep insulin levels as low as possible if we have cancer, to try to keep the tumor from growing.   If we can keep the diet under control, or exercise to keep glucose levels and insulin levels low, we have a much better chance of slower growth of the tumor.  Our research would also argue that pharmacological intervention would be more effective if we keep insulin levels low.”

Even better:  Keep insulin levels as low as possible anyway, whether you have cancer or not.  “This is a powerful potential cancer-prevention mechanism,” says Howard Soule, Ph.D., Executive Vice President and Chief Science Officer for the PCF.  “Reducing processed sugar may turn out to be even more important for cancer prevention than treatment.”

Can we learn to use cancer’s sweet tooth as a weapon against it?  Cantley’s research has already led to the development of several PI3K-inhibiting drugs: idelalisib, approved by the FDA in 2014 for treatment of lymphoma and leukemia and alpelisib, approved in 2019 for treating breast cancers with mutations in PI3K.  But Cantley also believes that changing the diet – to one low in sugar, but also low in other carbohydrates, which can cause blood sugar to spike – can make cancer-fighting treatments work even better.  In a landmark 2018 paper published in Nature, Cantley and colleagues showed in mice that by severely restricting carbohydrates “and keeping the insulin level low, tumors would respond much more dramatically to drugs that are already approved to treat them.  Tumors we had never been able to shrink in mice, we could shrink with a low-glucose diet.

“That’s my obsession now, to get that message out there.  Endocrinologists tell patients to exercise more and eat less sugar to keep diabetes under control, but for me, it’s even more critical to keep insulin levels low in order to get better outcomes for cancer patients.”  Cantley’s research suggests that “if you have a mutation in the PI3K pathway that causes cancer, and you’re eating a lot of simple carbohydrates, every time your insulin goes up, it’s making the tumor grow.”

How can this knowledge help slow the growth of prostate cancer?  Here’s one example:  “For prostate cancer patients with low Gleason scores who are on active surveillance, it makes perfect sense to pay a lot of attention to what you eat.  Try to keep your consumption of sugary drinks as low as possible.  Keeping sugar down is the best thing you can possibly do.”  It used to be, Cantley notes, Japanese men hardly ever got prostate cancer.  “But second-generation Japanese Americans have prostate cancer in similar rates to Caucasians.  It’s clearly lifestyle,” the Western diet.  “The truth probably is that some Japanese men in their 90s had some level of prostate cancer, but didn’t consume enough sugar for the cancer to advance.”

Here’s another:  If you are on ADT for metastatic prostate cancer, you are more likely to gain weight, and also to develop insulin resistance.  One way to fight this is by limiting your sugar and simple-to-digest carbs.  Bonus: keeping insulin down may also help slow down the cancer.  Watch out for protein drinks, too; many are loaded with sugar.

What about the ketogenic diet?  It’s low in carbs and high in fats.  “I’m not preaching the ketogenic diet; I don’t eat it myself,” says Cantley, who says he weighs the same now as he did in high school.  “I eat what my grandparents ate:  a healthy diet, lots of raw vegetables, some animal fat, healthy vegetable fats, an intermediate amount of protein.  I don’t avoid fats, but I prefer olive oil on salads, and healthy fats from fish and avocado,” instead of loading up on butter and cheese.  “I eat more protein than the ketogenic diet would recommend, and I do occasionally eat rice and pasta.”

But here’s the kicker:  “The one thing I’m fanatic about is not drinking anything with sugar:  no orange juice, no apple juice, no soda.  I’ll eat an orange, but I won’t grind it up and drink it.”  Sugar in liquid form is rapidly digested, which results in “glucose peaks, followed by insulin peaks.”

What about alcohol?  “A dry martini is probably safer than wine; there’s not much sugar in there.”  However, Cantley adds, “I do drink wine, but as low in sugar as possible.”

Exercise is a great way to divert sugar into someplace safe:  the muscles.  “Muscle is where you store a lot of sugar in your body.  If you drink a sugary drink after exercising, your insulin goes up, and you drive all that glucose into your muscle.  Whether you’re exercising at the time you drink a sugary drink, or you just put on muscle from exercise in general, there’s still a benefit: insulin won’t spike.”   However, exercise doesn’t make it safer to drink a lot of sugary drinks, because…

Sugary drinks are bad.  It’s not just sodas; sweet teas and coffee drinks have more sugar than you may realize.  Even sports drinks are loaded with sugar.  In 2019, Cantley and colleagues published another landmark paper in Science, involving mice with polyposis syndrome (mice genetically predisposed to developing polyps in the colon).  They demonstrated that sugary drinks can dramatically drive the growth of intestinal polyps.  “We gave mice high-fructose corn syrup, and their polyps grew two to three times faster.”  Fructose is a different sugar from glucose, and although “fructose is not consumed by tumors, it goes straight to the liver and turns into fat.  Fructose makes you fat.  But the other issue is that intestinal epithelial cells can directly consume fructose.  We think this explains why there has been a doubling to tripling rate of colorectal cancer in young adults.”

Consuming sugar in liquid form is worse than having that same amount of sugar in solid form.  Cantley explains:  “If you eat an apple, it takes a long time to get to the colon.  By the time it gets there, all that sugar has leached out.  But if you have that same amount of sugar in a drink, that watery sugar gets to the colon pretty quickly.  That’s independent of the insulin elevation (discussed above), and it’s another scary reason why young people should avoid drinking sugary drinks, no matter how much you exercise.  You may be a champion marathon runner, but if you’re drinking sugary drinks all the time to keep up your energy, this is a real warning that you should pay attention to.”

Now, back to prostate cancer:  Would taking a PI3K-inhibitor help slow cancer’s growth?  As is often the case with prostate cancer, it’s not that simple.  It turns out that there are two different kinds of PI3K, an alpha and a beta form that can contribute to prostate cancer.  “When prostate cancer loses PTEN, it uses PI3K alpha and beta form redundantly to drive the tumor.”  This means that a drug that targets only the alpha form probably won’t be as effective in prostate cancer as in other forms of cancer, where only the alpha form of PI3K is involved.

However, “our preclinical findings are overwhelmingly supportive, and the retrospective data in patients strongly suggests” that one day, in addition to surgery, radiation, hormonal therapy or other treatments for prostate cancer, patients will be prescribed a precision diet to make the treatment more successful.  “The more we learn about cancer metabolism, we are understanding that cancers are addicted to particular things.  For many cancers, that thing is sugar.”

In addition to the book, I have written much more about prostate cancer on the Prostate Cancer Foundation’s website, pcf.org. The stories I’ve written are under the categories, “Understanding Prostate Cancer,” and “For Patients.”  As Patrick Walsh and I have said for years in our books, Knowledge is power: Saving your life may start with you going to the doctor, and knowing the right questions to ask. I hope all men will put prostate cancer on their radar. Get a baseline PSA blood test in your early 40s, and if you are of African descent, or if cancer and/or prostate cancer runs in your family, you need to be screened regularly for the disease. Many doctors don’t do this, so it’s up to you to ask for it.

©Janet Farrar Worthington

 

 

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Whack-a-Mole and Prostate Cancer

Oligometastasis:  Good News from the ORIOLE Study

To the growing and hopeful list of strategies for attacking prostate cancer, let us add this approach:  Whack-a-Mole.

That’s how Johns Hopkins radiation oncologist Phuoc Tran, M.D., Ph.D., describes it to his patients.  The actual scientific name for this highly sophisticated strategy is stereotactic ablative radiotherapy (SABR, highly focused, intense doses of radiation), for men with oligometastasis – up to three small bits of cancer that have broken away from the main prostate tumor and started to grow elsewhere.

Previously, I wrote on Vital Jake and also on the Prostate Cancer Foundation’s website, about the Baltimore ORIOLE study, led by Tran, who also contributed greatly to our book.  Tran was enrolling patients in a small study to see if men with oligometastasis would benefit from SABR in addition to treatment of their primary tumor.

His strategy was a new one – part of a general rethinking of what represents curable prostate cancer.  The boundary used to be very clear:  prostate cancer was either confined to the prostate or prostate bed, or it wasn’t.   Like a light switch with no dimmer, there was no in-between:  a man with only one metastasis was believed to face the same fate, eventually, as a man with widespread metastases.  It was just a matter of time.

But Tran believed that the lines of prostate cancer were not so clear-cut as scientists had assumed; that instead of two circles – localized and metastatic cancer – that didn’t connect, we might be dealing with a Venn diagram, with oligometastasis as the critical area where the two circles overlap.  “It may be that the window of curability is wider than we thought,” he said last year, and we all hoped that he was right.

Tran and colleagues at Johns Hopkins, Stanford, and Thomas Jefferson University recently published results of the ORIOLE Phase 2 clinical trial in JAMA Oncology.  The results are promising:  54 men with oligometastasis were randomly assigned either to treatment with SABR or to observation.  To detect and keep track of the oligometastases, the study used PSMA-PET scanning, which uses a small molecule linked to PSMA (prostate-specific membrane antigen, found on the surface of prostate cancer cells) as a radioactive tracer.  This PSMA-targeting tracer can highlight areas of cancer as small as a BB – much smaller than can be seen on regular PET or CT imaging.  “PSMA-PET allows us to treat lesions we otherwise couldn’t see,” Tran explains.  “A CT or bone scan would miss those lesions, and patients would presumably not do as well.”

At six months, 61 percent of the men in the observation group progressed – compared to only 19 percent of the men who received SABR.  “We also saw a significantly decreased risk of new metastatic lesions using PSMA PET-CT” says Tran.  “The men in the SABR group did considerably better.  This is a definite signal that we can perhaps modify metastatic disease.”

This was a Phase 2 study, and “we need larger Phase 3 trials,” he says.  “But this is very positive, and we hope that in the future, we will be able to change the course of metastatic disease in some men.” 

Some interesting points here:  First, Tran and colleagues hope that “complete metastatic ablation of oligometastatic prostate cancer may provide an alternative to early initiation of androgen deprivation therapy (ADT).”  The key question, Tran says, is, “can we alter the natural history of metastatic prostate cancer with metastasis-directed therapy (MDT)?”  They don’t know the answer yet.  Most men with oligometastatic disease who get these spots of cancer zapped don’t experience a complete drop in PSA.  This, Tran says, suggests that “residual micrometastases are present but undetectable.” Does SABR simply reset the clock – does it keep pushing the snooze button?  Or, as the scientists hope, does it make the cancer less likely to form new metastases?

Bad Pioneers on a Bad Journey:  Tran and other scientists theorize that the spread of cancer is a story of colonization.  A few pioneers set forth on a journey to a new land.  At first, it’s touch-and-go; their survival is tenuous.  Just think of the early colonists in the U.S., from England, France, or Spain.  Until they took root in the new land, these nascent colonies were frail:  they needed reinforcements from their mother countries – medicine, weapons, tools, food – and “eventually they did survive.”  So it may be with the seeds of cancer; either the cancer cells themselves, or their messages (in the form of genetic and chemical telegrams) are dispatched to the primary tumor, the mother country.  If the mother country is no more – if it has been eradicated by surgery or radiation – then small cancer outposts might get similar support from visiting each other.  But if those outposts are destroyed by SABR, even if there are a few cancer cells remaining in the tissue or bloodstream, it doesn’t matter:  the environment is too hostile, and the numbers are too few for new colonies to survive – “or, if they did, it would take much longer.”

“It’s like Whack-a-Mole”:  In the ORIOLE trial, Tran and colleagues looked for circulating tumor DNA (ctDNA), and identified certain gene signatures that can tell if a man is more likely to respond to SABR.  “Patients who don’t have these mutations responded very well,” he says.  They also have learned from this and other research that men with oligometastasis fall into three basic groups.  “Some men do really well after one course of SABR,” with no recurrence of cancer.  A second group of men have a small recurrence.  “Another site pops up; a microscopic metastasis that we couldn’t see before establishes itself into a macroscopic metastasis.  It’s a limited return of cancer and it responds to another round of SABR.”  Then some men, after a few months, have multiple new areas of cancer.  “For these men, the SABR doesn’t control the disease at all.”

Imagine a green lawn, with one or two dandelions, Tran tells his patients:  “You can pluck those two or three weeds, and wait and see.  Sometimes you get lucky; sometimes another weed or two pops up, and you pluck them.  It’s like Whack-a-Mole.  You can do that for a while,” with repeated SABR treatments.  As the scientists reported:  “If a single round of MDT arrests the progression of some, but not all, lesions, subsequent rounds of MDT might salvage the remaining disease, until what remains is inadequate to support a metastatic phenotype.” Basically, for some men, a treatment strategy might be to keep knocking the cancer down until, like a prizefighter who’s taken one too many blows to the head, it can’t get back up.  Imagine:  punch-drunk prostate cancer that may still be staggering around, but can’t raise a fist.  Wouldn’t that be nice!

That probably won’t work in every man, Tran says.  “Unfortunately, sometimes there will be a whole bunch of seeds all at once, and at that point, you need weed killer all over the lawn,” or systemic therapy.  However, SABR plus ADT, androgen-blocking drugs, or chemo might one day provide “the multipronged attack required to cure this disease.”

Looking ahead:  In a follow-up trial, called RAVENS, men with oligomestatic prostate cancer are randomly given either SABR alone, or SABR plus radium-223 (Xofigo).  “What we have seen in the men in that second group – the ones who have more isolated spots of cancer popping up – is, they’re not recurring where they received the SABR, but in areas that were microscopic, and commonly in the bone.”  Radium-223 targets cancer in bone.  “It releases a radioactive particle that is very toxic but is so focused that it only kills in a radius of two-three cell depths.  It’s ideal for microscopic disease.”

More and larger studies are needed, but in the future, Tran envisions, men with oligometastasis will require more vigilant monitoring, and ideally, regular follow-up PSMA-PET scanning.  “This has the potential to be practice-changing.  We are very excited by our results, and by the potential to modulate the course of metastatic prostate cancer.”

In addition to the book, I have written about this story and much more about prostate cancer on the Prostate Cancer Foundation’s website, pcf.org. The stories I’ve written are under the categories, “Understanding Prostate Cancer,” and “For Patients.”  As Patrick Walsh and I have said for years in our books, Knowledge is power: Saving your life may start with you going to the doctor, and knowing the right questions to ask. I hope all men will put prostate cancer on their radar. Get a baseline PSA blood test in your early 40s, and if you are of African descent, or if cancer and/or prostate cancer runs in your family, you need to be screened regularly for the disease. Many doctors don’t do this, so it’s up to you to ask for it.

 ©Janet Farrar Worthington

 

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