Stronger associations with body size have been found in women with estrogen receptor and progesterone receptor positive (ER+PR+) BC (Potter et al. 1995; Huang et al. 2000; Colditz et al. 2004; Suzuki et al. 2009), those not using menopausal hormone therapy (HT) (Morimoto et al. 2002; Friedenreich 2001; Feigelson et al. 2004), or with longer time since menopause (Chu et al. 1991; Magnusson et al. 1998; Macinnis et al. 2004). Here, ESR1 is linked to breast cancer.