Elevation of Free β Subunit of Human Choriogonadotropin and Core β Fragment of Human Choriogonadotropin in the Serum and Urine of Patients with Malignant Pancreatic and Biliary Disease¹

Human choriogonadotropin (hCG), its free β subunit (βhCG), and the core βhCG fragment (cβhCG) were measured by highly sensitive time-resolved immunofluorometric assays in the serum and urine of 29 patients with pancreatic cancer, 7 patients with biliary cancer, and 45 patients with benign pancreatic or biliary diseases. The results were compared with those of an age- and sex-matched reference population of nonpregnant women and men. Of the various forms of hCG assayed in serum, βhCG showed the best diagnostic accuracy, and cβhCG was the best marker in urine. Elevated serum concentrations of βhCG were observed in 72% of the patients with pancreatic cancer, in 6 of 7 patients with biliary cancer, and in 9% of those with benign disorders. The serum concentrations of cβhCG were elevated in 45%, 57%, and 2%, respectively, and those in urine in 55%, 71%, and 11%, respectively. The molar concentrations of cβhCG in serum were mostly lower than those of βhCG. Thus βhCG secreted into serum appears to be the main source of cβhCG in urine. Provided that they are measured by sufficiently sensitive and specific assays, βhCG in serum and cβhCG in urine appear to be useful markers for pancreatic and biliary cancer.