ESR1 and breast carcinoma: Others have suggested that these variants are associated with reduced breast cancer risk among women with lower levels of estrogen [62, 63], and these findings complement those emerging from some of the studies on mammographic density: Among a population of pre- and postmenopausal women, the minor allele of the rs9340799 SNP was associated with decreased mammographic density, while no association was found for ERα rs2234693 [29].