Treatment with Talzenna should be initiated and supervised by a physician experienced in the use of anticancer medicinal products. Patient selection Breast cancer: Patients should be selected for the treatment of breast cancer with Talzenna based on the presence of deleterious or suspected deleterious germline BRCA mutations determined by an experienced laboratory using a validated test method. Genetic counselling for patients with BRCA mutations should be performed according to local regulations, as applicable. Prostate cancer: There is no requirement for tumour mutation testing for selection of patients with mCRPC for treatment with Talzenna.