Predictive Power of Human Chorionic Gonadotropin in Post-Molar Gestational Trophoblastic Neoplasia: A Longitudinal Roc Analysis

[Background]The present study aims at identifying an applicable longitudinal marker from the serum human chorionic gonadotropin (hCG) levels during 3 weeks after mole evacuation for predicting the gestational trophoblastic neoplasia (GTN) in patients with partial or complete molar pregnancy.[Methods]In this historical cohort study, 201 documents of patients with hydatidiform mole (according to their pathological reports) were investigated. A two-stage shared random effects model was used to describe the relationship between repeated measures of β-hCG (as a longitudinal indicator) and incidence of GTN. A receiver operating characteristic (ROC) curve was used to determine the power of repeated β-hCG values for predicting GTN.[Results]Among all patients, 171 cases (85.1%) had spontaneous remission and GTN was detected in 30 cases (14.9%). The modeling approach used in the current study revealed that the repeated measures of β-hCG concentration (in weeks 0, 1, 2, and 3) can correctly classify approximately 86.7% of patients with GTN and 83.0% of patients without GTN. The repeated measures of β-hCG concentration had higher predictive accuracy than cross sectional values of this marker for early detection of GTN.[Conclusions]In general, findings of the present study showed that the three-week β-hCG concentration is a powerful marker for predicting GTN in women with molar pregnancy (with AUC of 91.2%). Thus, monitoring the three-week trend of this marker is recommended for early detection of this malignancy in these women.