After adjusting for age at mammogram, BMI, menopause (premenopause/natural menopause/surgical menopause), parity, age at first birth, HRT, type of mammogram and time of follow up, there was a clear association between MD and subsequent BC development among BRCA1/2 mutation carriers, with a statistically significant dose-response trend (P value <0.001). Here, BRCA1 is linked to breast cancer.