The results of a German case-control study suggest that cumulative lifetime exposure to overweight is a greater contributor to colorectal carcinoma (CRC) risk than previously believed based on a single BMI assessment.
Although being overweight is associated with an increased risk of cancer, this risk may have been underestimated because previous research determined BMI only once and did not take into account cumulative lifetime exposure. In this case-control study initiated in Germany in 2003, height and self-reported weight from the age of 20 years onwards were documented every 10 years for 5,635 subjects with CRC and 4,515 control subjects. By linear interpolation, BMI was calculated for each age year and based on this, the weighted number of years of overweight or obesity (WYOs) was determined. Subsequently, associations with CRC risk were estimated for both BMI at different ages and for WYOs by multiple logistic regression.
The mean (SD) age of the patients (n = 5,635) and controls (n = 4,515) was 68.4 (10.9) and 68.5 (10.6) years, respectively; 59.7% and 61.1% were male. The researchers found an association between WYOs and CRC risk, with adjusted ORs increasing from 1.25 (95% CI 1.09-1.44) to 2.54 (95% CI 2.24-2, 89) for the first to fourth quartiles of the WYOs versus participants who remained within the normal weight range. Each SD increase in WYO was associated with a 55% increase in CRC risk (adjusted OR 1.55; 95% CI 1.46-1.64). This OR was higher than that per SD increase in (excess) BMI at any time, which ranged from 1.04 (95% CI 0.93-1.16) to 1.27 (95% CI 1.16 -1.39).
Li X, Jansen L, Chang-Claude J, et al. Risk of Colorectal Cancer Associated With Lifetime Excess Weight. JAMA Oncol. 2022 Mar 17. Online ahead of print.