Dietary Intervention and BRCA Penetrance

Insulin-like growth factor I (IGF-I) and other markers of insulin resistance (IRm) might modulate the penetrance of BRCA genes mutation. The investigators have designed a demonstration project with BRCA mutation carriers (with or without a previous diagnosis of breast cancer) to test: 1. whether a lifestyle intervention significantly reduceIGF-I and the other IRm (randomized trial). 2. whether mutation carriers with a previous diagnosis of breast cancer have higher IRm than carriers without breast cancer (case-controlstudy). 3. whether IRm and their change over time affect subsequent breast cancer incidence and prognosis (cohort follow-up). The investigators expect to significantly reduce IGF-I and IRm, to find that BRCA mutation carriers with a previous breast cancer have higher IRm levels, and, in the long term, that women with persistent higher IRm levels have higher penetrance and worst prognosis. Confirming a significant reduction of IRm and the impact of their levels on prognosis would help to develop primary prevention recommendations for high risk families.