BMI, long-term changes in BMI, and risk of cancer mortality in a large cohort study.

1502 Background: There are indications of an association between Body Mass Index (BMI) and risk of different cancer types. There is dispute whether this association differs between males and females. Methods: We studied the association of BMI at the first survey with risk of mortality from the most common types of cancer (lung, colorectal, breast and prostate cancer) in a large general population-based cohort study (Vlagtwedde-Vlaardingen, 1965-1990) with follow-up on mortality status until 2009. Additionally, we assessed this association based on tertiles of the annual change in BMI (defined as the difference between BMI at last survey and first survey divided by the time between last and first survey). We used 3 categories of BMI (< 25 kg/m2, 25-30 kg/m2, and ≥ 30 kg/m2) and changes in BMI (< 0.02 kg/m2/yr, 0.02-0.2 kg/m2/yr, and > 0.2 kg/m2/yr) in the analyses. The multivariate Cox regression model was adjusted for age, smoking, gender. Analyses were additionally stratified by gender and smoking. Results: Among all 8645 subjects, 1194 died due to cancer (lung cancer: 275; colorectal cancer: 134; breast cancer: 117; prostate cancer: 83). Mortality from all types of cancer was significantly increased in subjects with BMI > 30 kg/m2 (HR (95 % CI)) = 1.22 (1.00-1.48)), especially in females (1.38 (1.06-1.81)) and in never smokers (1.39 (1.02-1.90)). Prostate cancer mortality was significantly increased in males with BMI 25-30 kg/m2 (2.04 (1.90-3.83)) and > 30 kg/m2 (2.61 (1.02-6.67)). This association between prostate cancer mortality and BMI was higher in smokers. Lung cancer mortality risk was decreased in subjects with BMI 25-30 kg/m2 (0.71 (0.54-0.93)) and > 30 kg/m2 (0.82 (0.50-1.32)), especially in males, in smokers, and in smoking males. There were no significant associations between BMI and colorectal or breast cancer mortality nor between change in BMI and mortality from all analyzed types of cancer. Conclusions: We show that an increase in BMI is associated with an increased risk of mortality from all types of cancer in females and with an increased mortality risk from prostate cancer in males but with a decreased lung cancer mortality risk, especially in males. More research is needed into the biological mechanisms that link BMI to cancer.