However, contrary to what we found in the main study population, a subset analysis including only incident breast cancer cases found no significant association between mammography behaviour and HER2 status (non-screeners ORHER2-negative vs HER2-positive (reference): 0.87 [0.68–1.12], p = 0.286; unaware ORHER2-negative vs HER2-positive (reference): 0.95 [0.61–1.47], p = 0.811) (Additional file 1: Table S3). Here, ERBB2 is linked to breast cancer.