HER2‐low breast cancer had a higher proportion of HR‐positive patients (85.5%) compared to HER2‐0 (71.6%, p < 0.001), with similar results for ER‐positive and PR‐positive proportions (84.5% vs. 69.9%, p < 0.001; 74.8% vs. 63.0%, p < 0.001). Here, ESR1 is linked to breast cancer.