SF3B1 mutations have been identified in uveal melanoma (15%–29%), cutaneous melanoma (1%), pleural mesothelioma (2%), pancreatic ductal adenocarcinoma (3%), breast cancer (2%–4%), and prostate cancer (1.1%), while U2AF35 mutations were found in lung adenocarcinoma (3%) and prostate cancer (0.5%) [8,57]. This evidence concerns the gene SF3B1 and breast cancer.