Body size, weight change, and risk of colon cancer.
BACKGROUND
Epidemiologic studies have consistently reported positive associations between obesity and colon cancer risk for men, but the evidence is less consistent for women. Few studies have investigated effects of weight change on colon cancer risk.


METHODS
Using the Melbourne Collaborative Cohort Study, which recruited men and women mostly in 40 to 69 years of age, we investigated associations between weight and body mass index (BMI) at age 18 years and at study entry and weight change since age 18 years and colon cancer. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression.


RESULTS
During follow-up of 16,188 men and 23,438 women for 14 years on average, we ascertained 569 incident colon cancers. Weight and BMI at study entry were positively associated with colon cancer risk for men [HR, 1.12 (95% CI, 1.04-1.21) per 5-kg increment; HR, 1.39 (95% CI, 1.12-1.71) per 5 kg/m(2)], but not women. Risk of colon cancer was not associated with weight or BMI at age 18 years. Adult weight change was positively associated with colon cancer risk for men (HR, 1.11 per 5-kg increment; 95% CI, 1.03-1.20), but not women (HR, 1.00; 95% CI, 0.94-1.07). Men who gained ≥20 kg from age 18 had an increased risk of colon cancer compared with men whose weight was stable (HR, 1.47; 95% CI, 0.94-2.31).


CONCLUSIONS
Weight gain during adult life increases men's risk of colon cancer.


CONCLUSIONS
Avoiding excessive weight gain might help reduce colon cancer risk for men.
Bassett
Julie K
JK
Cancer Epidemiology Centre, Cancer Council Victoria, Carlton, Victoria, Australia. julie.bassett@cancervic.org.au
Severi
Gianluca
G
English
Dallas R
DR
Baglietto
Laura
L
Krishnan
Kavitha
K
Hopper
John L
JL
Giles
Graham G
GG
D000328:Adult; D000368:Aged; D015992:Body Mass Index; D049628:Body Size; D003110:Colonic Neoplasms / Q000150:complications / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D016016:Proportional Hazards Models; D012307:Risk Factors; D015430:Weight Gain