6533b856fe1ef96bd12b2f3a

RESEARCH PRODUCT

Effects of lifestyle and diet as modifiers of risk of breast cancer (BC) in BRCA1 and BRCA2 carriers.

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1505 Background: Mutations in the BRCA1/2 genes confer a high lifetime risk of BC. Penetrance varies among populations and individuals suggesting that non-genetic factors may modify the inherited risk. Knowledge of modifiable factors will help to develop preventive strategies. Methods: Information on physical activity (PA) (current PA and in the adolescence) and smoking was collected in 892 women (W) with a BRCA1/BRCA2 germ-line mutation (582 with BC, 45,62% BRCA2) from 279 families, followed at three Spanish Genetic Counseling Units, 481of these W also answered a food frequency questionnaire. Participants gave their consent and the study was approved by the ethics committee. The association between BC, lifestyle factors and dietary patterns (Mediterranean and Western) associated with BC were studied using logistic regression. Huber-White robust estimators of variance were employed to take into account correlations between family members. Age, menopausal status, specific mutated gene, BMI, parity and oral contraception were included as co-variables. BC was classified as HR+/+,- or HR-. Results: W who did PA daily had half the risk of BC than sedentary W (OR:0,53;p=0,043 for current PA;OR:0,40;p=0,007 for PA in the adolescent) and no differences were observed between BRCA1 and BRCA2 carriers. Also, W who daily exercised in both periods had a reduction of their BC risk (OR:0,22;p<0,001). The effect of PA was particularly important among premenopausal W (p-het<0,05). PA in the adolescent decreased the risk of all type of tumors. Nevertheless, alcohol intake, smoking habit and type of diet, did not significantly modify BC risk in this BRCA W. Conclusions: Our preliminary data suggest a clear reduction in BC risk among BRCA1/2 carriers who exercise regularly, mainly during the adolescence, and could be considered as potential modifiable factor for BC prevention in these group of W.