Today's Edition
(THE NEW YORK TIMES NEWS SERVICE)
A first-of-its kind study adds powerful new evidence to research showing that exercise improves cancer survival.
The study, a randomised 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% lower risk of dying and a 28% lower risk of recurrent or new cancer than those in the control group.
Earlier research had suggested such a benefit, but the data was 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, Booth said.
Eighty percent of patients in the exercise group remained disease-free after five years, compared with 74% 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, 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,” Booth said.
But in 30% to 40% 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, 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 analyse them to shed light on whether these factors might be driving the improved survival.
