Human chorionic gonadotropin free beta-subunit measurement as a marker of placental site trophoblastic tumors
Harvey, R.A.; Pursglove, H.D.; Schmid, P.; Savage, P.M.; Mitchell, H.D.C.; Seckl, M.J.
Journal of Reproductive Medicine 53(8): 643-648
2008
ISSN/ISBN: 0024-7758 PMID: 18773632 Document Number: 627649
To evaluate the utility of free human chorionic gonadotropin beta-subunit (hCGbeta) proportion of total hCG measurement to distinguish placental site trophoblastic tumor (PSTT) from more common forms of gestational trophoblastic disease (GTD). Serum samples collected from PSTT, persistent trophoblastic disease (PTD) and choriocarcinoma patients were used for retrospective analysis of free hCGbeta-subunit. Results were reported as a percentage of total hCG using our in-house competitive radioimmunoassay. The percentage of free hCGbeta was significantly greater in serum from 18 PSTT patients, yielding a median value of 45.5% than in a combined GTD group of 49 PTD and 12 choriocarcinoma patients. Receiver operating characteristic analysis confirms that the percentage free hCGbeta distinguishes PSTT from GTD patients. Choriocarcinoma patients had significantly higher hCGbeta measurements than PTD patients and were not well distinguished from PSTT patients. Our findings show that an elevated proportion of free hCGbeta-subunit is a helpful but not definitive test to discriminate PSTT from other forms of GTD.