Exercise tied to better colon cancer survival odds

People with colon cancer who spend more time walking and fewer hours on the couch are less likely to die over the seven to eight years after being diagnosed, a new study suggests.

The findings don't prove exercise itself boosts a person's survival chances, researchers said. But the pattern held even after the study team took into account how advanced patients' cancers were, their age and other aspects of their diet, lifestyle and health.

"Any activity is better than none," including walking, stretching and gardening, said Peter Campbell, the lead researcher on the study from the American Cancer Society.

"Five to ten minutes at a time is fine, and the type of activity we're talking about here, this isn't marathon running or climbing the Alps."

Campbell's analysis included about 2,300 people who developed colon cancer out of an initial pool of 184,000 volunteers in a cancer prevention and nutrition study launched in 1992.

Over an average of eight years after their diagnosis, 846 people with colon cancer died - including 379 from cancer.

The researchers found that study participants who exercised the most - equal to two and half hours of walking per week or more - both before and after being diagnosed were 28 to 42 percent less likely to die during the follow-up period than those who barely exercised at all.

Spending six or more hours of leisure time on the couch daily before diagnosis, compared to less than three hours, was tied to a 36 percent higher chance of dying. Being sedentary after a cancer diagnosis was linked to a 27 percent increased risk of death - although that particular finding could have been due to chance, the researchers noted this week in the Journal of Clinical Oncology.

To account for the fact that very sick people can't exercise, Campbell and his colleagues excluded anyone who died within two years of their last survey, and found similar results.

Researchers have known for a while that obesity and exercise affect a person's risk of getting colon cancer in the first place, said Dr. Jeffrey Meyerhardt from the Dana-Farber Cancer Institute in Boston, who has also studied exercise and colon cancer survival.

"The question when you're a patient with colorectal cancer is, ‘Do those things matter once I get the disease? Are there things I can do in addition to standard treatment to reduce my risk of recurrence?'" he told Reuters Health.

Researchers said there are a couple of possible explanations for why exercise, both pre- and post-diagnosis, might benefit people with cancer.

"What we think is at least part of what is happening is, people are going into surgery and adjuvant treatment in a more fit state," Campbell told Reuters Health.

In addition, he said, "If you're active both before and after diagnosis, there are a lot of changes that occur in your blood," such as in levels of insulin and other hormones.