ESR1 and breast cancer: In 2007, Rakha et al7 reported that patients with single hormone receptor–positive BC have more advanced clinicopathological features than patients with ER-positive/PR-positive subtypes and that patients with single hormone receptor–positive BC have favorable features compared with the ER-negative/PR-negative subtype; however, no difference in outcomes was detected between patients with ER-positive/PR-negative tumors and those with ER-negative/PR-positive tumors regarding lymph node status and BC survival.