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Monkey Wrench in the Works:  How Exercise Helps Sabotage Prostate Cancer

Fighting Prostate Cancer with Exercise (Part 1)

Being sedentary, smoking, excess weight, and foods that are inflammatory: these things create a hospitable environment that encourages prostate cancer.  Here are some things you can do to roll up the welcome mat and slow down prostate cancer – even advanced disease.

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.”

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 West Los Angeles VA Medical Center, was asked this question at a PCF-sponsored panel discussion on the effects of diet and lifestyle in advanced prostate cancer and survivorship.  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.

Results of several large studies suggest that exercise reduces the risk of dying of prostate cancer by 30 percent, and the risk of dying from any cause 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 and slow their PSA velocity.  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.

In related research, UCSF epidemiologist Stacey 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! (See Part 2)

Read next, Part 2: What Kind of Exercise is Good for Me?

Janet Worthington
Janet Farrar Worthington is an award-winning science writer and has written and edited numerous health publications and contributed to several other medical books. In addition to writing on medicine, Janet also writes about her family, her former life on a farm in Virginia, her desire to own more chickens, and whichever dog is eyeing the dinner dish.