Exercise and Colorectal Cancer Recurrence
CR Magazine: Collaberation – Results

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Here’s how to get your 18 MET-hours this week and lower your colorectal cancer risk.

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By Rabiya S. Tuma

A Step (or Leap, or Jump, or Stretch) in the Right Direction

Colorectal cancer survivors who exercise regularly may cut their risk of recurrence

By Rabiya S. Tuma


In the fall of 2001, Bea Wells, then 55, decided to enroll in a research study testing the potential impact of regular exercise on the risk of developing cancer. She thought it would be a good opportunity to start working out. But when doctors saw the results of her colonoscopy, a prerequisite for joining the study, they referred her to a surgeon rather than a physical trainer. Instead of working out, she was soon being treated for stage III colon cancer.

Yoga illustrationWhile undergoing chemotherapy the following spring, however, Wells decided again to begin an exercise program. She joined Team Survivor, an organization that promotes exercise for female cancer survivors. At the time, there was a growing body of data suggesting that exercise might help prevent cancers, and some cancer researchers were hopeful that post-diagnosis exercise might also be beneficial, reducing a survivor’s risk of recurrence.

Previously, Wells hadn’t taken exercise very seriously, but with her teammates exercise took on a whole new dimension in her life. “When I heard that Team Survivor climbs mountains every couple of years, I said, ‘When I get my knees replaced [due to injuries and osteoarthritis], I’ll have to climb a mountain.’ And I said that to too many people, so I couldn’t back out.” So at age 58, two years after chemotherapy, she had her knees replaced. And two years later, she climbed Washington State’s 12,276-foot Mount Adams with Team Survivor for her 60th birthday. Since then she has also completed a triathlon and walked the Seattle half marathon.

While Wells has been out burning calories, researchers have been shoring up evidence that shows that exercise really does lower the risk of recurrence for colorectal cancer patients. And they have found that survivors don’t have to go to such extreme lengths—or heights—to benefit. “We are not talking about training for a marathon,” says Leonard Saltz, an oncologist at Memorial Sloan-Kettering Cancer Center in New York City, who is a co-investigator on one of the key studies. “We are talking about moderate aerobic exercise, the same kind of exercise that everybody should be getting whether they are a cancer patient or not.”

In that study, which was published in the Journal of Clinical Oncology in 2006, oncologist Jeffrey Meyerhardt, of the Dana-Farber Cancer Institute in Boston, along with Saltz and others, compared the rate of recurrence in colorectal cancer survivors who exercised with the rate in survivors who did not. All of the 832 participants in their exercise study were already enrolled in a clinical trial comparing two chemotherapy regimens and had agreed to fill out questionnaires about their lifestyle habits, including exercise.

The bad news from the chemo trial was that there was no difference in outcome from the treatments. The good news was that the similarity in the drugs’ effects meant that Meyerhardt and his colleagues could investigate whether exercise affected recurrence. Because the patients did different types of exercise, the researchers converted their exercise practices into MET-hours: a measurement of the energy a person expends during exercise. One MET-hour, which stands for “metabolic equivalent task–hour,” is the amount of energy a person burns while sitting quietly for one hour.

Meyerhardt’s team found that men and women who participated in 18 to 27 MET-hours of exercise each week reduced their risk of recurrence by 49 percent compared with sedentary survivors—those who exercised three MET-hours per week or less. And according to Meyerhardt, doing 18 MET-hours a week is not difficult. It’s equivalent to walking at a modest pace for one hour, six days a week, or playing tennis or jogging for two-and-a-half hours each week. (For more activities, see the sidebar.)

To explore the role of exercise further, Meyerhardt and his colleagues also examined its effects on a second population of survivors. In this study, the investigators looked at the likelihood of death from colorectal cancer in 573 women who were diagnosed with non-metastatic colorectal cancer while participating in the large, ongoing Nurses’ Health Study. The team found that women who exercised for 18 MET-hours or more per week after their diagnosis were 61 percent less likely to die of their disease than sedentary women. The same amount of exercise also reduced by 57 percent the women’s risk of dying of any cause over 10 years of follow-up time. These results were also published in the Journal of Clinical Oncology in 2006.

 

(illustration: Scott Bakal)

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