Weight change later in life and colon and rectal cancer risk in participants in the EPIC-PANACEA study.

Background: A moderate association exists between body mass index (BMI) and colorectal cancer. Less is known about the effect of weight change.
Objective: We investigated the relation between BMI and weight change and subsequent colon and rectal cancer risk.
Design: This was studied among 328,781 participants in the prospective European Prospective Investigation into Cancer-Physical Activity, Nutrition, Alcohol, Cessation of Smoking, Eating study (mean age: 50 y). Body weight was assessed at recruitment and on average 5 y later. Self-reported weight change (kg/y) was categorized in sex-specific quintiles, with quintiles 2 and 3 combined as the reference category (men: -0.6 to 0.3 kg/y; women: -0.4 to 0.4 kg/y). In the subsequent years, participants were followed for the occurrence of colon and rectal cancer (median period: 6.8 y). Multivariable Cox proportional hazards regression analyses were used to study the association.
Results: A total of 1261 incident colon cancer and 747 rectal cancer cases were identified. BMI at recruitment was statistically significantly associated with colon cancer risk in men (HR: 1.04; 95% CI: 1.02, 1.07). Moderate weight gain (quintile 4) in men increased risk further (HR: 1.32; 95% CI: 1.04, 1.68), but this relation did not show a clear trend. In women, BMI or weight gain was not related to subsequent risk of colon cancer. No statistically significant associations for weight loss and colon cancer or for BMI and weight changes and rectal cancer were found.
Conclusions: BMI attained at adulthood was associated with colon cancer risk. Subsequent weight gain or loss was not related to colon or rectal cancer risk in men or women.