A significant increase was observed in the cause-specific hazard for breast cancer death for patients with a non-HER2-single subtype tumor (aHR 2.38, 95% CI 1.20–4.70, p = 0.014, n = 716; Table 2), which was confirmed in a subdistribution hazard model (p = 0.03). Here, ERBB2 is linked to neoplasm.