ERBB2 and neoplasm: Cox proportional-hazards models were used to evaluate potential confounding factors, revealing that pPGR is confounded by age (P-value = 0.06) and the T grading scale (P-value = 0.10) but independent of tumor grade (P-value = 0.01) and HER2 status (P-value = 0.02; Supplementary Data 9).