Stratification of colorectal cancer (CRC) risk was enhanced by joint consideration of the independent family history and genetic risk score predictors, according to an ongoing population-based, case-control study of patients recruited during 2003-2010.
Genetic risk score was calculated by genotyping 53 single-nucleotide polymorphisms reported in published literature to be associated with higher CRC risk for individuals of European descent. Seven genetic risk score groups – very low, low, low-medium, medium, medium-high, high, and very high – were established according to categories generated on the basis of weighted risk allele distribution among controls. Family history referred to CRC in first-degree and second-degree relatives. Selected potential confounders included age, sex, body mass index, education, hormone replacement therapy in women, smoking, and colonoscopy history. Odds ratios with 95% confidence intervals were estimated by multiple logistic regression models that included adjustment for potential confounders. Statistical calculations examined individual and joint family history and genetic risk score associations with risk for CRC and the effect of potential confounding factors.