Alpha fetoprotein determinations in germ cell tumors of testis.

Alpha fetoprotein was demonstrated in 15 of 115 patients with histologically proved germinal testicular neoplasms. Alpha fetoprotein was detected in patients only with embryonal carcinoma and teratocarcinoma; determinations were negative in all cases of pure seminoma, teratoma, and choriocarcinoma. Of 15 patients having detectable alpha fetoprotein, 14 had Stage III disease and one had Stage II disease. When alpha fetoprotein is present, it usually heralds progression of the disease and therefore may serve as a valuable biologic marker to monitor response to therapy.