Two models have shown potential in predicting the histology of residual masses: Vergouwe’s model, based on six predictive factors (histology of the primary tumor, serum alpha-fetoprotein (AFP) levels before chemotherapy, human chorionic gonadotrophin (hCG), lactate dehydrogenase (LDH), residual mass size measured by CT, and variation in mass size) [20]; and Leão’s model (Princess Margaret model), based on four predictive factors (presence of teratoma in the orchidectomy, pre-chemotherapy AFP, size of masses before chemotherapy, and variation in mass size during chemotherapy) [21]. This evidence concerns the gene AFP and teratoma.