Detection of AFP and HCG in metastatic testicular cancer after treatment with chemotherapy or radiation therapy.

We used an indirect immunoperoxidase technique to detect alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) in tissue sections of nine metastatic germ cell tumors excised after treatment with chemotherapy or radiation therapy, and correlated the results with the serum levels of AFP and HCG. In all but 1 case yolk sac tumor (YST) was the only histologic type that reacted for AFP (AFP+) and syncytiotrophoblasts (STB) were the only histologic type that reacted for HCG (HCG+). Among 5 cases with normalization of the serum AFP before surgery, 3 were associated with YST-/AFP-, 1 with YST+/AFP+, and 1 with YST+/AFP- metastases; and among 4 cases with normalization of the serum HCG all were associated with STB-/HCG- metastases. Among 3 cases with persistent elevation of the serum AFP, 1 was associated with YST+/AFP+, 1 with YST+/AFP-, and 1 with YST-/AFP- metastases; and of 2 cases with persistent elevation of the serum HCG, 1 was associated with STB-/HCG- and 1 with STB+/HCG+ metastases. These data suggest that marker normalization in the face of persistent tumor results primarily from eradication of YST and STB, but also from treatment-induced inhibition of AFP and HCG synthesis or secretion.