Early prediction of post-molar gestational trophoblastic neoplasia and resistance to methotrexate, based on a single serum human chorionic gonadotropin measurement

Background. Clinicians are unable to provide individualized counseling regarding risk of progression for pa-tients with a complete hydatidiform mole (CHM). We developed nomograms enabling early prediction of post-molar gestational trophoblastic neoplasia (GTN) and resistance to methotrexate (MTX) based on a single serum human chorion gonadotropin (hCG) measurement. Methods. We generated two nomograms with logistic regression: to predict post-molar GTN, and MTX resis-tance. For patients with high probability to progress to post-molar GTN or MTX resistance, we determined hCG cut-offs at 97.5% specificity to select patients for additional-or adjustments in current treatment. Results. The nomograms had a good to excellent ability to distinguish either between patients with unevent-ful hCG regression versus progression to post molar GTN, or between patients cured by MTX versus patients in whom resistance would occur. At 97.5% specificity, we identified 66% (95%CI 56-75) of the 149 patients who would progress to post-molar GTN, four weeks after initial curettage. For patients treated with MTX, we identi-fied 55% (95%CI 23-83) of the 43 patients who would become resistant, preceding their third course at 97.5% specificity. Conclusion. The nomograms and cut-off levels can be used to assist in counseling for patients diagnosed with CHM. (c) 2021 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).