Age-specific rates of ER- breast cancer cease to increase after 50 years of age, while the age-specific rates of ER+ breast cancer continue to increase after 50 years of age (Tarone & Chu, 2002), which might be explained by the finding that proliferation rate of ER+ cells increased with age (Shoker et al., 1999). Here, ESR1 is linked to breast carcinoma.