It also showed good calibration in most subgroups of the validation data set, except for underestimating the risk of cancer-specific mortality of ER–/PR–/HER2– patients (4.65 events vs 11 events, P=.004) and underestimating the risk of disease progression of the 45 to 54-year-old (25.95 vs 39, P=.01), urban (58.91 vs 77, P=.01), and HR+/HER2+ (18.34 vs 33, P<.001) subgroups. The gene discussed is ERBB2; the disease is cancer.