Trophoblastic proteins as tumor markers in nonseminomatous germ cell tumors

In order to examine the relative usefulness of measurements of oncoplacental proteins as tumor markers in patients with nonseminomatous germ cell tumors, the authors measured alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), pregnancy-specific beta 1-glycoprotein (SP1), human placental lactogen (hPL), and placental cystine aminopeptidase (oxytocinase, CAP) in serial blood samples obtained from 26 men with these neoplasms. HCG and AFP were each elevated in 62% of the patients and both were elevated in 38%. SP1 and hPL were increased in 31% and 12%, respectively. None of the patients had elevated CAP activity. Serum hCG and SP1 concentrations were strongly correlated (r = 0.78, P less than 0.001). No patient had an elevated SP1 without a concomitant elevation in serum hCG. Serial measurements of hCG and SP1 indicated that they were concordant in five of the eight patients in whom both were elevated, and AFP and hCG were concordant in only one half of the ten patients in whom both markers were elevated. The number of patients with hPL elevations were too few for meaningful comparison of this marker with the others. These results indicate that measurements of SP1, hPL, and CAP do not provide additional useful information over that obtained from measurements of hCG and AFP in patients with nonseminomatous germ cell tumors.