Prostate Cancer Canada Network

In The News

Well-Done Meat Consumption May Increase Prostate Cancer Risk
Research into the dietary habits of about a thousand men from the Cleveland area has found that a high consumption of meats, especially of red meat prepared by grilling, is positively associated with an increased risk of developing aggressive prostate cancer. This particular study, which was led by Dr. John Witte of the University of California, San Francisco (UCSF), has a number of limitations, but it does add support to other investigations connecting meat consumption with cancer risk.

Toronto researchers speculate regarding a link between prostate cancer and oral contraceptive use
Very preliminary and speculative research, designed to spark further inquires, suggests that there may be a connection between oral contraceptive use and rising rates of prostate cancer. One theory is that the widespread use of birth-control pills in various populations may result in a higher level of estrogen in the environment, which might, in turn, increase prostate cancer risk.

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Exercise

The exact benefits of exercise for men who have been diagnosed with prostate cancer are difficult to pinpoint, but evidence suggests a probable link between increased physical activity and decreased prostate cancer risk. Here is some of the evidence on which experts base this probability.

A review article published in 2004, tells us that, in all the research on prostate cancer and exercise published between 1976 and 2002, “16 out of 27 studies reported reduced risk in men who were most active; in nine out of 16 studies the reduction in risk was statistically significant.” The average risk reduction discovered in these studies ranged from 10 to 30 per cent. (See an abstract of this study.)

A more recent report, published in the Journal of Clinical Oncology, suggests that physical activity may improve survival among men diagnosed with prostate cancer. This study compared the physical activity and rates of overall and prostate-cancer mortality of 2,705 men in the Health Professionals Follow-Up Study. All the men had non-metastatic prostate cancer and were followed between 1990 and 2008. The results are promising.

Men who were physically active were at a lower risk of dying, from prostate cancer or other causes.
Exercise at any intensity seemed to lower the overall risk of mortality, but the more vigorously one exercised, the greater the benefit. (For example, men who walked for at least 90 minutes per week at a normal or brisk pace had a 46 per cent lower risk of death than men who walked at a slower pace and for less time.)
Men who did at least 3 hours per week of vigorous exercise, such as biking, tennis, jogging, or swimming, had a 61 per cent lower risk of prostate-cancer death.

Why might exercise help prevent prostate cancer from recurring or growing? Researchers hypothesize that exercise

modulates hormone levels,
prevents obesity,
enhances immune functioning, and
reduces oxidative stress.

A few of these points may need explaining. Remember, these are still hypotheses being tested.

Hormone levels
Prostate cancer growth has been linked to higher levels of the male sex hormone testosterone, and several studies have discovered a correlation between exercise that gets the heart pumping (aerobic exercise) and a reduction in testosterone. Physical training also appears to reduce stress hormones and metabolic hormones, such as insulin and insulin-like growth factors (IGFs), which are thought to stimulate tumour formation.

Excessive weight
Obesity is definitely risky for men with prostate cancer. One study out of Harvard found that obese men with prostate cancer were 2.5 times more likely to die from the disease than those of a healthy weight. The thinking is that the higher insulin levels of the overweight men put them more at risk. (See an abstract of this study.)

Immune system
Regular exercise has also been linked to an increase in the number and activity of natural killer cells, the part of the immune system that attacks cancer cells.

Oxidative stress
Regular exercise has also been associated with a reduction in oxidative stress and inflammation. To understand oxidative stress, you need to know a few things. First, our bodies constantly react with oxygen as we breath and our cells produce energy. And oxidation-reduction reactions, which involve the transfer of electrons in the atoms or groups of atoms that compose our cells, are essential to this process. It’s part of how oxygen travels. The trouble is that oxidation (the loss of electrons) and reduction (the gain of electrons) need to be balanced for good health. Oxidative stress is an imbalance in this natural process. It allows free radicals to build up in the body. (A free radical is a highly reactive molecule with an unpaired electron.) And these free radicals can disrupt normal cellular processes and cause cell damage if antioxidants (which neutralize or “mop up” free radicals) are not present in sufficient quantities. Inflammation, another natural process that helps us fight off infections, can contribute to oxidative stress if it is long-term or chronic. Habitual exercise may be one of the best natural antioxidants, and research suggests that it helps stave off chronic inflammation too.

Exercise and men on hormone therapy
Androgen deprivation therapy (ADT), also known as hormone therapy or androgen suppression therapy (AST), is a wonderful tool in the fight against prostate cancer. But it can have some unintended and negative side effects. Among these are muscle loss and a decrease in bone mass or bone density. Exercise can help men combat these side effects.

Researchers from Johns Hopkins reported in 2007 that walking briskly for 20 to 30 minutes 5 to 6 times a week actually helped men receiving ADT increase their bone mass. The men in the control group, who were on ADT and did not exercise, experienced a 2.14 per cent decrease in their bone mass. (See this article.)

In 2009, a study published in the Journal of Clinical Oncology, concluded, “A relatively brief exposure to exercise significantly improved muscle mass, strength, physical function, and balance in ... patients undergoing AST.”

In sum
All things considered, exercise is a good bet for men who have been treated with prostate cancer. Take it from the Prostate Cancer Foundation’s booklet Nutrition, Exercise and Prostate Cancer:

Exercising for durations of approximately one hour each day is an excellent strategy for weight maintenance, while progressive resistance training has been shown to build muscle, increase resting metabolism, improve glucose tolerance, increase strength, muscle function, and aerobic fitness, contribute to increased bone density, and improve quality of life.

These benefits not only affect you while you are battling prostate cancer; the lifestyle you choose to maintain can keep you living well after cancer.

What should my exercise regimen look like?
Of course, the answer to this question depends on where you are in your prostate cancer treatment, your prognosis, your general state of health, and your current level of physical fitness---to name just a few variables. But if you are contemplating becoming making regular exercise part of your fight against cancer, here are some important guidelines:

1. Talk to your doctor before starting any exercise program, and discuss

whether it is safe for you to start,
what types of exercise are right for you, and
how often (frequency), how hard (intensity), and how long (duration) you should exercise each week, to begin with.

2. Start slowly and build up gradually.

3. Aim to do aerobic exercise, such as walking, jogging, cycling, or swimming, three to five times a week for at least fifteen to forty minutes. (Remember, you will probably have to work up to this frequency and duration.) Daily exercise of less duration is also appropriate.

4. Aim to do resistance exercise two to three times a week for about twenty minutes to an hour. Start with easy weights and only a few repetitions; and don’t start at all until you have consulted a qualified instructor and told him or her about your current health challenges, fitness level, and resistance exercise experience.

5. Don’t overdo it, but try to exercise at a moderate intensity level. This is the level at which you elevate your rate of breathing and your heart rate, but you can still talk to a buddy.

6. As you become more fit, increase the duration of your exercise before you increase its intensity.

7. Make sure you warm up, stretch, and cool down. Any good book on jogging or power walking or your exercise of choice will offer suggestions here; and following them will help you avoid injuries.

8. Drink water to remain hydrated.

9. Listen to your body; stop exercising immediately if you feel chest or joint pain, are dizzy or lightheaded, experience unusual fatigue, or have trouble breathing.

For excellent, practical information about how to begin and maintain an exercise program for prostate cancer prevention, read Challenging Prostate Cancer: Nutrition, Exercise, and You.