ESR1 and neoplasm: In 36 patients (25 ER + , 11 ER−) with tumor fraction ≥ 0.05, we observed an overall accuracy of 0.92 (AUC = 0.96), including 0.96 accuracy (AUC = 0.98) for samples with higher tumor fraction (≥0.1, n = 24) and 0.85 accuracy (AUC = 0.90) for lower tumor fraction (0.05–0.1, n = 12) (Fig. 4e, Supplementary Fig. 13b, c, Supplementary Data 15).