BRCA1 and breast cancer: In postmenopausal women, high young-adult BMI was associated with reduced breast cancer risk in BRCA1 carriers compared to women with a normal BMI, although statistical significance was only reached in the category of low compared to normal BMI (< 18.5 kg/m2 vs. 18.5 to < 25 kg/m2: HR 1.67, 95% CI 1.09–2.56).