December 28, 2005

Obesity Linked to Poor Colon Cancer Survival

By Will Boggs, MD

NEW YORK (Reuters Health) - People who are obese around the middle and are physically inactive have poor odds of survival after a diagnosis of colorectal cancer, according to a new report.

"We have now shown that modifiable lifestyle factors that were known to reduce the incidence of colorectal cancer can also reduce the mortality in cases diagnosed with the disease," Dr. Andrew M. M. Haydon told Reuters Health. "This strengthens the argument supporting the public health message of 'healthy living."'

Haydon, from Monash Medical School in Melbourne, Australia, and colleagues used data from the Melbourne Collaborative Cohort Study to investigate whether physical activity and obesity influenced the survival of more than 40,000 patients diagnosed with colorectal cancer between 1990 and 1994.

Patients who reported regular exercise before their colorectal cancer was found were 31 percent less likely to die from the cancer than were non-exercisers, the investigators report in the medical journal Gut. In fact, 73 percent of exercisers survived at least five years, compared with 61 percent of non-exercisers.

This improvement in survival "is at least as large as" what is achieved with add-on chemotherapy, the investigators note.

As well as inactivity, a greater percentage body fat, bigger waist circumference, and/or greater weight were also associated with worse survival, the researchers note.

"Similar data have recently ... demonstrated similar effects in other cancers (breast and prostate) with respect to physical activity," Haydon commented.

"We need to point out that our study related to measurements taken prior to diagnosis," he added, "and we cannot say that increasing physical activity or losing weight post diagnosis is of any proven benefit at this stage."

SOURCE: Gut, January 2006.