 In those with mutations in the breast cancer susceptibility genes "BRCA1" or "BRCA2", or who have a family history of breast cancer, use of modern oral contraceptives does not appear to affect the risk of breast cancer.The association between breast feeding and breast cancer has not been clearly determined; some studies have found support for an association while others have not.In the 1980s, the abortion–breast cancer hypothesis posited that induced abortion increased the risk of developing breast cancer.