ESR1 and cancer: Of the 43,230 primary invasive lobular breast cancer patients with no comorbid conditions included in this study, 27,962 (64.7%) patients had ER+PR+ tumors, 5,000 (11.5%) patients had ER+PR-disease, 585 (1.4%) women had ER-PR+ cancers, and 9,683 (22.4%) women had ER-PR- subtype of tumors.