ESR1 and breast carcinoma: Furthermore, on the basis of a very stringent multiplicative model, the borderline significance P values for the interaction between rs12539530 and rs827421 (P = 0.07) and between rs12539530 and rs7739506 (P = 0.09) are in line with the suggestion that an interaction between rs12539530 and ESR1 polymorphism is linked to breast cancer risk.