How Exercise Helps Sabotage Prostate Cancer
Exercise makes the body a lot less hospitable to cancer. Or, if you think about prostate cancer as the machine that it is, hijacking countless normal body mechanisms so it can grow and spread: Exercise throws a monkey wrench in the works!
UCLA urologist William Aronson, M.D., was asked recently: “What do your patients with prostate cancer ask you about exercise?” His response: “None of my patients ask about exercise.” That’s a shame.
Sadly, exercise is not on the radar for many men with prostate cancer, and it ought to be, because it extends life, improves quality of life, and slows the progression of prostate cancer. Aronson, who also sees patients at the Greater Los Angeles VA Hospital, was asked this question at a panel discussion sponsored by the Prostate Cancer Foundation (PCF) on the effects of diet and exercise in advanced prostate cancer and survivorship. I covered this discussion for the PCF’s website. Notably, the focus here wasn’t on preventing prostate cancer, or delaying the time to treatment – although studies suggest exercise may contribute to each of these. Instead, it was for men already living with cancer that has escaped the prostate – and the overwhelming consensus among the panelists is that exercise and diet can make a big difference. Hear these words: If you have prostate cancer, no matter what stage, you can help fight it with exercise!
Results of several large studies suggest that exercise reduces the risk of dying of prostate cancer by 30 percent, and the risk of dying of other causes by 40 percent, says UCSF epidemiologist June Chan, Sc.D., who was also part of the panel discussion. Chan is a pioneer in studying the benefits of exercise in prostate cancer. Back in 2011, Chan and colleagues found a lower risk of progression of cancer in men who engaged in vigorous exercise. But in later studies, “we saw benefit with just brisk walking.”
Just what is it that makes exercise beneficial? What does it do? It may help to think about prostate cancer as a weed. Exercise may not act on prostate cancer directly, but if it disrupts the environment – affects the plant’s access to sunshine, soil, air, or water – then the plant is not going to grow as well. In other words, exercise makes the body a lot less hospitable to cancer. Or, if you think about prostate cancer as the machine that it is, hijacking countless normal body processes and mechanisms so it can grow and spread: exercise throws a monkey wrench in the works.
Exercise lowers insulin and insulin-like growth factor, says Harvard scientist Edward Giovannucci, M.D., Sc.D., professor of epidemiology and nutrition and also part of the panel discussion. “Physical activity improves insulin sensitivity, which is important for diabetes.” Insulin, a hormone that regulates the metabolism of carbohydrates and fat, can play a role in cancer, too; so can a closely related hormone, called insulin-like growth factor. Both of these hormones also affect cell growth and division, Giovannucci adds. “If you have higher levels because you’re physically inactive or maybe a bit overweight, or maybe you don’t have the best diet, those high levels will sometimes lead to diabetes, sometimes lead to heart disease, and sometimes they lead to cancers. Prostate cancer is one of those cancers that is probably sensitive to these key hormones.”
The Heart of the Matter
Chan brought up a very interesting study at the panel discussion: the ERASE trial, published in JAMA Oncology in 2021. Canadian investigators looked at the effects of 12 weeks of high-intensity interval training on patients at the early end of the prostate cancer spectrum: men on active surveillance who had very low-risk to favorable intermediate-risk prostate cancer. At first glance, you might not think this study applies to men with advanced prostate cancer. Not only did participants have localized prostate cancer, but this was aerobic exercise: supervised sessions on a treadmill, at which the men achieved 85 to 95 percent of peak oxygen consumption, compared to a control group of men who continued their normal exercise routines. But wait: in just three months, exercise was shown to decrease the men’s PSA levels, slow their PSA velocity, and slow prostate cancer cell growth. Obviously, more studies are needed to look at the effects of exercise on men at every stage of prostate cancer; in fact, the investigators noted that “to date, only one exercise study has been conducted in this clinical setting.” But still, these are exciting results!
Even more exciting: Participants in the ERASE trial showed improvement in cardiorespiratory fitness. For men with prostate cancer, cardiovascular health should be a concern, and improving it should be a goal. “Cardiovascular disease is a major cause of illness and death for patients with prostate cancer,” says Harvard epidemiologist Lorelei Mucci, Sc.D., who moderated the panel discussion. These are also words for you to take, well, to heart: If you have advanced prostate cancer, and you’re on ADT, you should know that ADT can have cardiovascular side effects. But exercise helps protect the heart.
In related research, UCSF epidemiologist Stacy Kenfield, Sc.D., Chan’s colleague in the Department of Urology, recently led a small study specifically looking at high-intensity interval training in men with advanced prostate cancer, and a larger study is planned, “designed to look at overall survival and progression-free survival benefits and biomarkers,” says Chan.
The bottom line: In addition to whatever exercise does specifically to discourage prostate cancer from growing – which is still not fully understood – exercise accomplishes what many forms of therapy do not: it prolongs life. It lowers your risk of dying from prostate cancer and from heart disease. Exercise is good medicine, and the good news is that you don’t have to sprint on a treadmill or cycle at Tour de France-level speed to achieve a benefit: even moderate exercise can make a big difference! More about exercise and advanced prostate cancer in the next post. Note: I know the monkey in this illustration is smoking a cigar, and smoking is bad for prostate cancer. But his tough-guy attitude conveys what I hope you will have: a can-do spirit to fight prostate cancer!
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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