Effect of Genetic and Lifestyle Risk Factors on the Association Between Body Mass Index and Personal History of Breast and Ovarian Cancer in the Bright Pink Population

Abstract

Objective: To investigate the effect modification by genetic and potential lifestyle risk factors on the association between BMI and breast and ovarian cancers diagnosed among women 20-40 years of age.Methods: We conducted a case-control analysis with 1511 breast cancer cases and 6044 controls and 1267 ovarian cancer cases and 5068 controls between 20-40 years of age. The study population and data were obtained from the Bright Pink, a national non-profit organization dedicated to the prevention and early detection of breast and ovarian cancer in young women. Cases and controls were frequency matched by age category. The association between BMI and Breast and ovarian cancers were modelled separately using logistic regression. Effect modification by hereditary gene mutations and behavioral factors including physical activity, cigarette smoking, alcohol consumption and oral contraceptive use were evaluated in each of the final models at the 0.10 significance level.Results: Compared to the normal weight group, the underweight group had more breast cancer diagnoses (OR adjusted 95% CI=1.31 [1.05, 1.64]) while the obese group had less (OR adjusted 95% CI=0.82 [0.70, 0.96]). Only women the underweight group were significantly more likely to have a personal history of ovarian cancer compared to the normal weight group (OR adjusted 95% CI=1.69 [1.32, 2.15]). Physical activity, alcohol consumption, and smoking were found to be effect modifiers in the associations between BMI and breast and ovarian cancers. Being underweight was related to increased personal history of breast and ovarian cancers among women who exercised regularly, were current smokers, or had >1 drink per day while the magnitude of association was attenuated among women who did not engage in these health behaviors.Discussion: Our study supports recent findings of BMI as a protective factor for premenopausal breast cancer in literature. Interaction between BMI and several behavioral factors suggest young, underweight women may have higher susceptibility to carcinogenic effects of environmental exposures in breast and ovarian cancer development. The results of this case-control analysis are subject to potential recall bias and reverse causality. Future prospective studies are needed to verify these findings.

Files

Additional details