ESR1 and breast cancer: After adjusting for significant prognostic variables (age, grade, tumor size, marital status, race, ER, PR, HER2, radiotherapy, chemotherapy) in the univariate analysis, multivariate analysis indicated that the overall mortality risk and breast cancer‐specific death risk were higher in the LN‐positive group than in the LN‐negative group (OS: HR = 1.743, 95% CI: 1.576–1.928, p < 0.001; BCSS: HR = 3.783, 95% CI: 3.143–4.553, p < 0.001).