Human chorionic gonadotropin in cancer

Human chorionic gonadotropin (hCG) is mainly used for detection and monitoring of pregnancy and pregnancy-related disorders but it is also an extremely sensitive and specific marker for trophoblastic tumors of placental and germ cell origin. Thus treatment of relapsing choriocarcinomas and testicular germ cell tumors is often initiated on the basis of rising hCG levels even in the absence of clinical or histological evidence of a relapse. While these tumors mostly produce the intact heterodimeric hormone consisting of an α (hCGα), and a β subunit (hCGβ), many nontrophoblastic tumors produce only hCGβ This is usually a sign of aggressive disease and elevated serum levels of hCGβ are strongly associated with poor prognosis. Elevated serum levels are observed in 45–60% of patients with biliary and pancreatic cancer and in 10–30% of most other cancers. Methods that detect hCG and hCGβ together are mainly used for measurement of hCG-like immunoreactivity in serum. However, the reference range for hCG is 5–8 fold higher than that for hCGβ and thus moderately elevated levels can be identified only with a specific and sensitive hCGβ assay.