For example, later age at menarche and breastfeeding is tied to a reduced BC risk for all subtypes, whereas later age at menopause and primigravida is linked to an increased BC risk for only some subtypes (tubular A, tubular B, and HER2).[4] However, the extent to which reproductive factors affect BC remains unclear due to the inherent statistical errors, which cannot be eliminated. This evidence concerns the gene ERBB2 and breast cancer.