For patients with HER2-enriched breast cancer and TNBC, respective cumulative incidence of brain metastasis at five years was 15.7% (95% CI: 12.9%–18.5%) and 15.8% (95% CI: 13.5%–18.1%), compared with 3.7% (95% CI: 3.0%–4.4%) for luminal A type and 7.2% (95% CI: 5.6%–8.8%) for luminal B type (Table 2 and Fig. 2a). This evidence concerns the gene ERBB2 and breast cancer.