Therefore, the first main message from our analysis is that, during the oncofertility counselling of premenopausal women with HER2-positive early breast cancer, the discussion around the risk of gonadotoxicity with the proposed treatment as well the need for having access to the available strategies for ovarian function and/or fertility preservation should be driven mostly by the type of chemotherapy regimen proposed and by the age of the patient (i.e., the two most important determinants of this risk). The gene discussed is ERBB2; the disease is breast carcinoma.