Identification of chemotherapeutic refractory cases based on human chorionic gonadotropin values among patients with low-risk persistent trophoblastic disease treated with 8-day methotrexate-folinic acid

Purpose: The aim of the present study was to establish the accurate cutoff points of post-treatment serum B-hCG values in identifying chemotherapeutic refractory cases among patients with low-risk persistent trophoblastic disease (PTD) treated with 8-day methotrexate-folinic acid as the primary therapy. Materials and methods: The values of serum Β-hCG measured before initiating treatment and weekly thereafter in 26 patients with low-risk PTD undergoing 8-day methotrexate-folinic acid treatment were analyzed. Thereafter, we determined the weekly cutoff points to identify the patient refractory for treatment by means of receiver-operating characteristic (ROC) plots analysis. Results: The values of cutoff points in the pretreatment, the post-treatment 1^st, 2^nd, 3^rd, and 4^th week were 18.6, 15.0, 5.4, 3.4, and 2.0ng/ml, respectively, and the value of accuracy during these weeks was appropriate (> 80%). When using the cutoff points of one and two weeks after initiating treatment, the accuracy in identifying chemotherapeutic refractory patients was 87.5% and 88.0%, respectively, with the highest values exceeding 85%. The sensitivity and specificity at one week were 92.9 and 80.0%, respectively. Similarly, the sensitivity and specificity at two weeks were 93.3 and 80.0%, respectively. Conclusion: These results suggest that the cutoff points of one and two weeks after initiating treatment are useful in identifying chemotherapeutic refractory patients among low-risk PTD patients, receiving 8-day methotrexate-folinic acid treatment.