title: Human chorionic gonadotropin free beta-subunit measurement as a marker of placental site trophoblastic tumors.
abstract: OBJECTIVE
  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).
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Charing Cross Oncology Laboratory and Trophoblastic Disease Centre, Charing Cross Hospital Campus of Imperial College Healthcare National Health Service Trust, London, UK. richard.harvey@imperial.nhs.uk
authors.forename: Richard A
authors.initials: RA
authors.lastname: Harvey
authors.forename: Howard D
authors.initials: HD
authors.lastname: Pursglove
authors.forename: Peter
authors.initials: P
authors.lastname: Schmid
authors.forename: Philip M
authors.initials: PM
authors.lastname: Savage
authors.forename: Hugh D C
authors.initials: HD
authors.lastname: Mitchell
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Seckl
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D011247:Pregnancy; D012372:ROC Curve; D018245:Trophoblastic Tumor, Placental Site / Q000175:diagnosis*; D014594:Uterine Neoplasms / Q000175:diagnosis*
chemical_list: D014408:Biomarkers, Tumor; D018997:Chorionic Gonadotropin, beta Subunit, Human