Predicting gestational trophoblastic neoplasia (GTN): is urine hCG the answer?

BACKGROUND Previous studies on the significance of hCG to predict gestational trophoblastic neoplasia (GTN) have been too small for robust conclusions to be reached. Our aim in this study was to analyse the significance of urine hCG in predicting GTN in a large population. METHODS Details of 3926 patients were available for analysis. Information regarding age, dates of diagnosis and registration, urine hCG levels, antecedent pregnancy and chemotherapy were prospectively collected and used for analyses. Patients were stratified into different groups according to urine hCG level (IU/L); < 50, 50-99, 100-249, 250-499, 500-999, 1000-9999 and ≥10,000. Multivariate analyses were used to identify the prognostic indicators of GTN. RESULTS Urine hCG and antecedent pregnancy were the most powerful indicators for developing GTN (P<0.01). None of the patients with partial mole and urine hCG <50 IU/L (Normal level=40 IU/L) developed GTN. The risk of GTN was >35% in all patients with urine hCG ≥500 IU/L. GTN developed in 70% of patients with complete mole and urine hCG ≥10,000 IU/L. CONCLUSION Urine hCG is sensitive test for GTN. Urine hCG level is a powerful prognostic indicator for the GTN. Patients with partial mole could be safely discharged from the surveillance programme once their hCG have normalised. Patients with urine hCG ≥249 IU/L, whether partial or complete molar pregnancy, appear to benefit from intensive surveillance. Prophylactic chemotherapy could be considered when there are problems with surveillance.