Placental proteins (SP1, hCG, PP5) and alpha 2-PAG in trophoblastic diseases.

455 serial serum samples from 41 patients with trophoblastic tumour were analysed. Pregnancy-specific beta-1 glycoprotein (SP1), human chorionic gonadotropin (hCG), and placental protein 5 (PP5) were measured by specific radioimmunoassay. Pregnancy-associated alpha 2-glycoprotein (alpha 2-PAG) was measured by electroimmunoassay. SP1 and hCG levels were high in 36 and 35 patients respectively; alpha 2-PAG concentration was also high in 29 patients. PP5 was found only in patients with a hydatidiform mole and it disappeared from serum within a few hours of evacuation. SP1 and hCG levels decreased during the course of the treatment but seronegativity was reached only after some months: hCG was still detectable after that and disappeared from the serum more slowly. Both parameters were sensitive indicators of residual tumour activity and indicated the need more effective treatment some months before clinical manifestations of recurrence became evident. In some patients only one of the tumour markers was present during follow-up, indicating the importance of careful monitoring including the measurement of serum SP1 and hCG levels. A positive correlation between alpha 2-PAG and hCG, SP1 and the clinical course was found only in 80% of patients a finding which demonstrates the limited value of alpha 2-PAG measurements.