A Cohort study found that women with positive BRCA1 and BRCA2 mutations developed a significant risk of breast cancer but only in the short term, while lifelong combined oral contraceptives (estrogen and progesterone) reduced the cancer risk, but some drugs like hormonal replacement therapy were found to interfere with this protective long term positive impact of this combined oral contraceptive [171]. Here, BRCA1 is linked to breast cancer.