Linear regression was adjusted for tumour size, histology, ER status, PR status, HER2 status, TN status and grade in the FOCUS study and the Nottingham Breast Cancer series (B 0.031, 95% CI 0.006–0.057, p = 0.016 and B 0.034, 95% CI 0.015–0.054, p < 0.001, respectively). Here, ERBB2 is linked to neoplasm.