Physical inactivity and obesity increase the risk of colorectal cancer but little is known about whether they influence prognosis after diagnosis.
Dr Haydon and colleagues from Australia identified incident cases of colorectal cancer.
The researchers assessed data from the Melbourne Collaborative Cohort Study, a prospective cohort study of 41,528 Australians recruited from 1990 to 1994.
Participants diagnosed with their first colorectal cancer between recruitment and 2002 were eligible.
|The benefit of exercise was largely confined to stage II and III tumors|
At the time of study entry, body measurements were taken and participants were interviewed about their physical activity.
The team obtained information on tumor site and stage, treatments given, recurrences, and deaths from systematic review of the medical records.
The researchers identified a total of 526 cases of colorectal cancer.
Median follow up among survivors was 6 years, and 208 deaths had occurred, including 181 from colorectal cancer.
After adjusting for age, sex, and tumor stage, the team observed that exercisers had an improved disease specific survival.
The researchers found that the benefit of exercise was largely confined to stage II and III tumors.
Increasing per cent body fat resulted in an increase in disease specific deaths.
Similarly, the team noted that increasing waist circumference reduced disease specific survival.
Dr Haydon's team concluded, “Increased central adiposity and a lack of regular physical activity prior to the diagnosis of colorectal cancer is associated with poorer overall and disease specific survival.”