PGR and breast neoplasm: Stratifying the breast tumors by ER status indicated that the rs3734091-TT genotype was strongly associated with ER-negative breast cancer (OR = 9.43, 95% CI 2.91-30.57, P = 0.0001) under a recessive model (Table 2), and similar associations were observed when the tumors were stratified by PR status (OR = 10.70, 95% CI 3.44-33.32, P < 0.0001).