Background: An hCG regression curve has been used to predict the natural history and response tochemotherapy in gestational trophoblastic disease. We constructed hCG regression curves in high-risk gestationaltrophoblastic neoplasia (GTN) treated with EMA/CO and identified an optimal hCG level to detect EMA/COresistance in GTN. Materials and
Methods: Eighty-one women with GTN treated with EMA/CO were classifiedas primary high-risk GTN (n = 65) and single agent-resistance GTN (n = 16). The hCG levels prior to each courseof chemotherapy were plotted in the 10th, 50th, and 90th percentiles to construct the hCG regression curves.Diagnostic performance was evaluated for an optimal cut-off value.
Results: The median hCG levels were 264,482mIU/mL mIU/mL and 495.5 mIU/mL mIU/mL for primary high-risk GTN and single agent-resistance GTN,respectively. The 50th percentile of the hCG level in primary high-risk GTN and single agent-resistance turnedto normal before the 4th and the 2nd course of chemotherapy, respectively. The 90th percentile of the hCG levelin primary high-risk GTN and single agent-resistance turned to normal before the 9th and the 2nd course ofchemotherapy, respectively. The hCG level of ≥ 118.6 mIU/mL mIU/mL at the 5thcourse of EMA/CO predictedthe EMA/CO resistance in primary high-risk GTN patients with a sensitivity of 85.7% and a specificity of 100%.
Conclusion: EMA/CO resistance in primary high-risk GTN can be predicted by using an hCG regression curvein combination with the cut-off value of 118.6 mIU/mL at the 5thcourse of chemotherapy.