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

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.
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.
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.
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.