The triple-negative subtype (ER−/PR−/HER2-) is associated with BRCA1 germline and somatic mutations [41] and our observation of a more than two-fold increase in odds of ER + PR+ breast cancer (vs. any ER- or PR-) among women jointly characterized as having late age at first pregnancy and unmethylated BRCA1 promoter is consistent with these findings. Here, PGR is linked to breast cancer.