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+β 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+β 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+β 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+β remain to be investigated prospectively.

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