In a sensitivity analysis excluding individuals without direct metastatic tumor subtyping and adjusting for receptor subtype only (HR + /HER2−, HR + /HER2 + , HR−/HER2−, HR−/HER2−), younger and older age were both associated with shorter OS (HR [95% CI] ≤35 years v. This evidence concerns the gene ERBB2 and metastatic neoplasm.