HealthDay News — Higher body mass index (BMI) is associated with a significantly increased risk for colorectal cancer (CRC) among men, whereas higher waist-to-hip ratio (WHR) is a strong risk factor among women, according to a study published online in BMC Medicine.
Caroline J. Bull, PhD, from the University of Bristol in the United Kingdom, and colleagues used data from the Genetics and Epidemiology of Colorectal Cancer Consortium, Colorectal Cancer Transdisciplinary Study, and Colon Cancer Family Registry (58,221 cases and 67,694 controls) to examine sex- and site-specific associations of adiposity with CRC risk. Additionally, adiposity-associated metabolites were studied to determine if they explain the association between adiposity and CRC.
The researchers found that in sex-specific Mendelian randomization analyses, higher BMI (per 4.2 kg/m2) was associated with higher odds of CRC among men (odds ratio [OR], 1.23; 95% confidence interval [CI], 1.08 to 1.38) and women (for BMI per 5.2 kg/m2: OR, 1.09; 95 percent CI, 0.97 to 1.22). WHR (per 0.07 higher) was more strongly associated with CRC risk among women (OR, 1.25; 95% CI, 1.08 to 1.43) than among men (OR, 1.05; 95% CI, 0.81 to 1.36). For 104 of 123 metabolites, there was an association seen with BMI or WHR (false discovery rate corrected P ≤ 0.05). While several metabolites were associated with CRC, the directions of the associations were not consistent with the mediation of positive adiposity-CRC relations.
“Adiposity was associated with numerous metabolic alterations, but none of these explained associations between adiposity and CRC,” the authors write. “More detailed metabolomic measures are likely needed to clarify the mechanistic pathways.”