Here we have used the same case-control study nested within the Melbourne Collaborative Cohort Study (MCCS) analysed before [6], to investigate if the association between DA, PDA and NDA and inherent risk of breast cancer, and the risk of masking vary by tumor characteristics, specifically size, grade, lymph node involvement, and ER, progesterone (PR), and human epidermal growth factor receptor 2 (HER2) status. Here, ERBB2 is linked to breast cancer.