The beta-subunit of chorionic gonadotrophin as a tumour marker in gestational trophoblastic disease.

The clinical usefulness of the serum level of the beta subunit by radioimmunoassay was evaluated in 96 patients with gestational trophoblastic disease. The measurement of the hormone-specific beta subunit has allowed a better understanding of the activity of the various types of disease, with a correlation between the initial serum levels and the different subtypes of hydatidiform mole, and the ability to predict the development of malignant sequelae. The phenomenon of trophoblastic persistence after uterine evacuation was confirmed: although the half-life of the beta subunit was 4 days during the early phase, there was an average period of 8 weeks before levels fell to negative and 12 weeks was the limit for spontaneous regression. The serial beta subunit levels were found to provide an accurate indication of the clinical course of the disease in untreated and treated patients, and treatment could be withheld after 3 consecutive weekly negative values.