Alcohol consumption and breast cancer risk -- Modification by genetic susceptibility

Abstract

Gene-environment and gene-gene interactions lie at the root of many human diseases. This thesis evaluated the risk of bias in the case-only design applied to studies of genetic interaction by way of a systematic review and meta-regression analysis. The case-only design was then used to investigate interactions between BRCA gene mutations and alcohol consumption among breast cancer patients, and the results were compared to a case-control analysis of BRCA mutation carriers with and without breast cancer. The systematic review suggests that the case-only design is unbiased when applied to studies of genetic interaction. The case-control analysis found that increasing wine consumption may reduce the risk of breast cancer among BRCA1 mutation carriers, and the results of case-only analysis may be compatible with this. Among BRCA2 mutation carriers, consumption of alcohol other than wine increased breast cancer risk in the case-only analysis while no association was observed in the case-control analysis.