In the HR+/HER2- stage I-III breast cancers with early (N = 103) and late (N = 167) recurrence, the most frequent alteration was PIK3CA mutation (39.8% vs 45.5%), followed by BRCA1/2 (11.7% vs 7.2%), AKT1 (7.8% vs 4.8%), ESR1 (3.9% vs 4.8%), PTEN (2.9% vs 2.4%), PALB2 (1.0% vs 1.2%), and PD-L1 amplification (0% vs 0.6%). This evidence concerns the gene ESR1 and breast cancer.