Detection of trophoblastic tumour activity by pregnancy-specific beta-1-glycoprotein.

Pregnancy-specific beta-1-glycoprotein (PSBG) and human chorionic gonagotrophin (hCG) were measured by specific radioimmunoassays in 73 serum samples from eight patients treated for gestational choriocarcinoma. Both markers were initially present in all cases, but at the time of writing both had levelled off in six cases and decreased markedly in two. Usually hCG was detectable for longer than PSBG during the course of chemotherapy. Both PSBG and hCG reappeared on clinical recurrence. However, at times during the follow-up period one trophoblastic marker only was expressed. This was hCG in most cases, but in one case PSBG alone was encountered. These results suggest that PSBG may serve as an additional marker for the detection of residual tumour growth in patients with trophoblastic tumours.