Prediction of Gestational Trophoblastic Neoplasia Based on Postevacuation Serum Human Chorionic Gonadotropin Concentrations

GTN is a general term for an extensive range of malignant trophoblastic diseases including invasive mole, choriocarcinoma, epithelioid trophoblastic tumors and placental site trophoblastic tumors. The aim of this study was to predict the risk of GTN in patients with molar pregnancy in Tehran.
All cases with partial and complete mole with a record of at least 4 titers of β-hCG were included in this study. Before and after fitting the appropriate model for calculating the area under the curve of each predictor variable, the type of the relationship (linear or non-linear) was first determined using locally weighted scatter plot smoothing (Lowess Smoother) and fractional polynomial regressionþ (Fracpoly); then, a model tailored to data processing was used for drawing the ROC diagram.
Nonparametric chi-square analysis indicated no significant difference between the components of high-risk molar pregnancy and GTN (P=0.39). Generally, among 201 cases of molar pregnancy, 61 (30%) had one of the components of high-risk molar pregnancy. The ROC curve with an AUC of 0.86 showed that the regression slope of β-hCG with 73% sensitivity and 88% specificity could be used as a predictor.
The serum β-hCG measurement after 21 days of molar pregnancy evacuation and the slope of the linear regression line of β-hCG were found be good tests to distinguish between patients who will benefit from spontaneous disease remission and patients developing GTN.