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The trial, in people treated for colon cancer, showed clear evidence that an exercise program lowered the risk of disease recurrence and death.
A first-of-its kind study adds powerful new evidence to research showing that exercise improves cancer survival.
The study, a randomized controlled trial of nearly 900 patients at 55 cancer centers in six countries, showed that people who participated in a structured exercise program lived longer without their cancer coming back and without the occurrence of new cancers. Participants in the exercise program had a 37 percent lower risk of dying and a 28 percent lower risk of recurrent or new cancer than those in the control group.
Earlier research had suggested such a benefit, but the data were from observational studies that did not prove a causal link, experts said.
“We now have definitive evidence that exercise is not just an intervention for quality of life and fitness. This is an intervention that improves survival and should be standard of care,” said Dr. Christopher Booth, the senior author of the paper and a professor of oncology at Queen’s University in Canada.
The study, which was published Sunday in the New England Journal of Medicine, looked at patients with Stage III or high-risk Stage II colon cancer who received standard surgery and chemotherapy treatment. Researchers randomly assigned these patients to a control group, which received educational materials promoting physical activity and healthy nutrition, or to a treatment group, which also received support from a “physical activity consultant” — a hybrid of personal trainer and life coach — over three years to increase their aerobic exercise and sustain it. Patients could choose a number of activities, such as biking, jogging, swimming or kayaking, but most opted for a brisk walk of 45 minutes four times a week, Dr. Booth said.
Eighty percent of patients in the exercise group remained disease-free after five years, compared to 74 percent of patients in the control group. After eight years, the exercise program had prevented one death for every 14 people who participated in the exercise arm of the study.
The reduction was specifically in colon cancer deaths, Dr. Booth said — not deaths from other causes, like cardiovascular disease.
“This is really wonderful news, particularly at a time when colon cancer rates are increasing among younger adults,” said Dr. Michelle Holmes, a professor of medicine at Harvard University who has studied lifestyle interventions to improve cancer survival and was not involved in the new study. She added that the improvement in disease-free survival was “in the same ballpark” as what observational studies across a range of cancers have shown, suggesting that the benefit of exercise extends beyond colon cancer.
Typically, colon cancer patients receive surgery and chemotherapy and then are sent home and followed intermittently, with loose guidance to exercise and follow a healthy lifestyle. “Essentially we would just cross our fingers and hope the cancer doesn’t come back,” Dr. Booth said.
But in 30 to 40 percent of patients, it does. Doctors said patients often ask what they can do after treatment to improve their outcomes. “Clearly an exercise program has to be right on that menu of things that we’re offering people as part of really routine care,” said Dr. Graham Colditz, an epidemiologist and associate director for prevention and control at the Alvin J. Siteman Cancer Center at Washington University who was not involved in the study.
It’s not clear how exactly exercise reduces the new onset or recurrence of cancer. Weight loss was the same between the two trial groups, Dr. Booth said, so that doesn’t appear to be the driver. But researchers have long shown that exercise improves insulin sensitivity and reduces inflammation. The researchers collected blood samples and will analyze them to shed light on whether these factors might be driving the improved survival.
Of course, the real-world impact of such an intervention will depend on how many people can take up and stick with an exercise program. This was a clinical trial in which patients were slightly younger and healthier than the typical cancer patient might be, and they were also already motivated to exercise. Even the control group increased their exercise levels, Dr. Booth said, though the treatment group increased them by much more.
Involving patients in a structured exercise program with ongoing support and accountability was key, said Kerry Courneya, lead author of the paper and a professor and Canada research chair in physical activity and cancer at the University of Alberta. The program included 48 sessions with a physical activity consultant over three years. The consultant helped troubleshoot problems, supported patients to find time to exercise and make it fun, and periodically assessed their physical fitness. The estimated total cost per patient was between $3,000 and $5,000, depending on the center, Dr. Booth said.
Terri Swain-Collins, a trial participant, said that when she first began, knowing she would be meeting with a consultant every two weeks forced her to stay on top of the exercise. “I was like, I’m doing this because I can’t go see her and not have done this,” Ms. Swain-Collins said.
“If I hadn’t had that, I wouldn’t have done it,” she admitted.
Ms. Swain-Collins, an X-ray technologist with a busy schedule, tried a few different things, including joining a gym and riding a stationary bike at home. Neither stuck. Walking ended up being her favorite activity. The consultant helped her fit it into her day, suggesting that she walk for longer when shuttling between the two hospitals where she worked or that she walk right after work, before getting tied up with dinner and chores at home. Her program ended in February, but she still walks for 45 minutes three times a week.
“That’s just part of my routine now. It’s awesome,” she said. After being sick with cancer and feeling like she had no control over what was happening to her, Ms. Swain-Collins said adopting an exercise regimen of her choosing was empowering. “It was like, OK, I can do this on my own time and figure it out, and this’ll be my thing I’m going to do for my own recovery,” she said.
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