In premenopausal women with HER2-positive early breast cancer candidates to undergo chemotherapy plus 1-year of trastuzumab-based anti-HER2 treatment as per standard of care [1], limited evidence exists to counsel them about the potential added risk of gonadotoxicity with the administration of targeted agents beyond the damage already caused by systemic cytotoxic therapy. The gene discussed is ERBB2; the disease is breast carcinoma.