A 27-year-old man has surgery for a testicular mass. Histologic sections reveal the mass to be a testicular yolk sac tumor. Which of the substance listed below is most likely to be increased in this patient's serum

Tumors sometimes secrete specific substances that appear in the serum. These tumor markers can be used clinically for diagnosis, for staging, and for following patients after surgery to look for recurrences of the tumor. Two impoant tumor markers associated with testicular neoplasms are a-fetoprotein (AFP) and human chorionic gonadotropin-b (hCG-b). Increased levels of AFP are associated with embryonal cell carcinoma or endodermal sinus tumor, whereas increased levels of hCG are associated with choriocarcinoma. Increased levels of both AFP and hCG are seen with mixed germ cell tumors. It is impoant to note that although seminomas may be associated with increased levels of hCG, pure seminomas are never associated with increased levels of AFP. Ref:- Harsha Mohan textbook of Pathology