(02-01-06) Physical inactivity, central obesity worsen survival of colorectal cancer

Physical inactivity and central obesity prior to a diagnosis of colorectal cancer are associated with poorer survival, according to a report in the January 2006 issue of Gut.

"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 from Monash Medical School, Melbourne, Australia told Reuters Health. "This strengthens the argument supporting the public health message of 'healthy living.'"
Dr. Haydon 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 study entry were 26% less likely to die and 31% less likely to die from colorectal cancer than were non-exercisers, the authors report. Five-year disease specific survival was 73% for exercisers and 61% for non-exercisers.
"This improvement in survival is at least as large as is achieved with adjuvant chemotherapy," the investigators note.
Exercise was most strongly associated with survival among patients with cancers that were stage II or III at diagnosis, the results indicate, and among patients whose cancers originated in the right colon.
Greater percent body fat, waist circumference, and/or weight were also associated with worse survival, the researchers note, whereas body mass index did not influence outcome.
The influence of obesity on outcomes did not depend on the stage of the disease at diagnosis, the report indicates, but the detrimental associations with a large waist circumference and high percent body fat seemed to be confined to patients whose tumors were in the left colon or rectum.
"Similar data have recently...demonstrated similar effects in other cancers (breast and prostate) with respect to physical activity," Dr. Haydon said. "We need to point out that our study related to measurements taken prior to diagnosis, and we cannot say that increasing physical activity or losing weight post diagnosis is of any proven benefit at this stage."
"Physical activity and excess body mass seem to affect colorectal cancer (among many other benign and malignant conditions) in its different stages of development," Nigel R. Hall from Addenbrooke's Hospital, Cambridge, UK writes in a related editorial.
"There is at least some expectation that long-term health and fitness programs might reap benefits not only in terms of reducing colorectal cancer incidence but in prolonging survival even if no cancer does occur."

Gut 2006;55:62-67,8-10.

Fonte: Reuters Health

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