The standard weapons in the fight against cancer surgery, chemotherapy and radiation may soon be joined by something far simpler: exercise. New research shows that regular physical activity helps reduce the risk of recurrence of breast cancer and slows the advance of prostate cancer.


In a few years, exercise will probably be prescribed regularly for cancer rehabilitation, said Melinda Irwin, an expert on cancer and exercise at Yale University School of Medicine. Personal trainers may join oncologists, surgeons and radiologists as members of the cancer-treatment team. Exercise will become a "targeted therapy, similar to chemotherapy or hormonal therapy," Irwin said.


Any regular physical activity the equivalent of a 30-minute walk, five times a week will do. "Don't think you have to work up a sweat or train for a marathon to benefit," Irwin said.


Exercise offers many other advantages: It fights the fatigue caused by cancer treatment, calms anxiety and helps survivors feel better about themselves and their bodies.


Some personal trainers now specialize in working with cancer patients, and more will soon be certified through a program of the American College of Sports Medicine. The Ridgewood YMCA offers a 12-week strength-training and fitness program for cancer patients and survivors.


There are 10 million cancer survivors in the United States, 22% of them women who have had breast cancer, 17% of them men who've had prostate cancer.


Heart attack patients are now routinely put on exercise plans. But workouts for cancer patients are neither prescribed by doctors nor covered by health insurance.


"We're where cardiac rehab was 20 years ago," Irwin said. Once exercise was shown through research to prevent fatal heart attacks, 12 weeks of rehabilitation became the standard of care for most heart patients. In fact, many hospitals opened cardiac rehab centers. One day, that will probably happen with cancer patients.


Researchers are working to understand how physical activity helps fight cancer. Their findings so far suggest that exercise:


       Reduces blood levels of insulin, a substance in the body that causes cells to divide and grow more quickly. Women with high levels of insulin have a slightly higher risk of breast cancer and a much higher rate of recurrence and death.

       Helps repair infection-fighting T-cells, restoring the immune system after it has been damaged by chemotherapy.

       Reduces levels of circulating estrogen and testosterone, two hormones linked with breast, endometrial and prostate cancers. Even with medication to suppress estrogen production, some estrogen is stored in fat cells. Exercise may help by converting fat to muscle.

       Prevents weight gain and promotes weight loss, important because obesity is associated with lower rates of survival for many forms of cancer. For women with breast cancer, obesity at the time of diagnosis, and weight gain afterwards, are associated with worse outcomes. The heavier and less active a person is, the more likely her cancer will return.


Most of the scientific work so far has focused on women with breast cancer, simply because there are so many. But studies have also shown exercise has positive effects for survivors of colorectal and prostate cancers. Among men older than 65, three hours of vigorous activity a week was associated with a decline in death from prostate cancer.


Exercise is now considered so beneficial that cancer experts are even encouraging patients to begin or resume exercise while treatment is under way. Workouts might need to be scaled back in intensity and pace, but "evidence strongly suggests that exercise is not only safe and feasible during cancer treatment, but that it can also improve physical functioning and some aspects of quality of life," according to the American Cancer Society.


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