ESR1 and neoplasm: After adjustment for covariates, including age, Ki-67, stage, tumor size, lymph node status, ER status, PgR status and pCR status, ER > 10% positivity remained significantly associated with better DFS than ER low positivity (HR, 0.325; 95% CI, 0.131–0.807: P = 0.015) but was not significantly associated with OS (HR, 0.441; 95% CI, 0.070–2.764: P = 0.382).