Different subtypes of breast cancer may have different risk factors. For instance, ER-positive breast cancer is often linked to hormonal factors such as early menstruation, late menopause, and hormone replacement therapy. HER2-positive cancers are less clearly linked to hormonal factors but are often associated with genetic mutations. TNBC is more prevalent in women with BRCA1 mutations and is also associated with younger age and African-American ethnicity.
