ESR1 and breast cancer: In addition, a single-nucleotide polymorphism G473A (rs1800449) resulting in an Arg158Gln mutation has been shown to be associated with increased risk of estrogen receptor (ER)-alpha-negative invasive breast cancer in African-American women [6], and subsequently with increased risk of breast cancer and ovarian cancer in Chinese women [52], [53], and with gastric cancer [54].