ERBB2 and breast cancer: After adjusting for covariates, women younger than 50 years were less likely to die from BC-specific death compared to women aged 50 to 69 years, particularly for ER + tumours [HR = 0.89 (95%CI: 0.82 to 0.96)], luminal A tumours [HR = 0.66 (95%CI: 0.51 to 0.86)] and HER2-enriched tumours, although the latter association with age was not statistically significant.