ESR1 and neoplasm: In a Cox proportional hazards model for DFS adjusting for age, stage, tumor grade, receipt of chemotherapy, receipt of adjuvant endocrine therapy, and HER2 status, ER category was not associated with DFS, but PR low status remained significantly associated with worse DFS (HR 2.2, p-value 0.003, 95% CI 1.3–3.8) (Table 3).