After the evacuation of a
hydatidiform mole, the
spontaneous regression or the persistent trophoblastic disease (PTD) needing
chemotherapy, is monitored by determining the serum
human chorionic gonadotropin (hCG) concentration. Hyperglycosylated hCG (
invasive trophoblast antigen, ITA) has been suggested to be of clinical value in the diagnosis and follow-up of
gestational trophoblastic disease including PTD. To further document the relationship between ITA and hCG in spontaneous post-molar regression and during
chemotherapy treatment of PTD, we used distinct immunoassays to measure the concentrations of hCG+beta and ITA in serum from three groups of patients after the evacuation of moles. For each group [uneventful post molar hCG regression, group 1; PTD treated with
Methotrexate (MTX) (mono-
chemotherapy), group 2; and PTD with MTX and poly-
chemotherapy (EMA-CO), group 3], we compared the time course of the serum concentrations after evacuation, and determined the disappearance rates (half-lives) within and between treatment groups. Significantly longer mean serum half-lives for hCG+beta and ITA were found in the poly-
chemotherapy (group 3: 3.02 and 2.51 weeks) as compared to the mono-
chemotherapy group (group 2: 0.96 and 0.90 weeks) and the uneventful regression group (0.81 and 0.66 weeks) (each, p=0.003), but no differences were observed between the mono-
chemotherapy and the uneventful regression group. Significantly shorter mean half-lives for ITA than those calculated for hCG+beta were observed in all three groups of patients. The implication and the possible clinical value of the more rapid regression of ITA to baseline levels as compared to hCG+beta remain to be investigated prospectively.