Women with high BMI at increased risk of colorectal cancer

A higher body mass index (BMI) is associated with an increased risk of colorectal cancer (CRC) in women, a study has shown. Moreover, the relation between BMI and microsatellite instability (MSI)-high CRC appears to be more robust than that between BMI and microsatellite-stable CRC, but validation in an independent cohort is warranted.

A total of 2,407 individuals and 2,454 control participants were recruited from a large German population-based case-control study. Standard interviews were conducted to obtain information on recent weight and height, as well as other demographic and lifestyle data.

The authors used multinomial logistic regression to estimate odds ratios (ORs) and 95 percent confidence intervals (CIs) for the relations between BMI and risk of CRC by major molecular pathological features: MSI, CpG island methylator phenotype (CIMP), B-Raf proto-oncogene serine/threonine kinase (BRAF) mutation, and Kirsten rat sarcoma viral oncogene homolog gene (KRAS) mutation.

Among women, a higher BMI differentially and more strongly correlated with risk of MSI CRC (OR per 5 kg/m², 1.69, 95 percent CI, 1.34–2.12; p_{heterogeneity}≤0.001), CIMP-high CRC (OR per 5 kg/m², 1.57, 95 percent CI, 1.30–1.89; p_{heterogeneity}≤0.001), BRAF-mutated CRC (OR per 5 kg/m², 1.56, 95 percent CI, 1.22–1.99; p_{heterogeneity}=0.04), and KRAS-wildtype CRC (OR per 5 kg/m², 1.35, 95 percent CI, 1.17–1.54; p_{heterogeneity}=0.01) compared with CRC risk in those with the molecular feature counterpart.

No meaningful difference in CRC risk were seen in men for the examined molecular feature pairs.

Effect modification by sex was present for the association between BMI and MSI CRC (p_interaction=0.04). In addition, CRC risk with the serrated pathway features in women was greater with higher BMI than that with the traditional pathway features (OR per 5 kg/m², 1.73, 95 percent CI, 1.28–2.34; p_{heterogeneity}=0.01).