ESR1 and breast cancer: HRD-gLOH was particularly high in the ER-positive/HER2-negative (43.2%, p = 0.0682 vs BC and p = 0.0306 vs N-CNS) and ER-negative/HER2-negative (70.5%, p = 0.0269 vs BC and p = 0.0039 vs N-CNS) BCBMs compared to both BCs and N-CNS (Table 2).