BRCA1 and neoplasm: In both the TCGA and METABRIC datasets, in the BECN1 deletion subgroup, low BRCA1 expression was not associated with ER-negative tumor subtypes, TP53 mutations or advanced tumor grade; in fact, in METABRIC, low BRCA1 expression was inversely associated with HER2-enriched (odds ratio 0.5 [95% CI 0.3–0.8], P = 0.0018) and grade III tumors (odds ratio 0.3 [95% CI 0.2–0.6], P5.5E− 04) (Supplementary Table 4).