The International Federation of Gynecology and Obstetrics (FIGO) 2000 scoring system classifies gestational trophoblastic neoplasia (GTN) patients into low- and high-risk groups, so that single- or multi-agent chemotherapy can be administered accordingly. However, a number of FIGO-defined low-risk patients still exhibit resistance to single-agent regimens, and the risk factors currently adopted in the FIGO scoring system possess inequable values for predicting single-agent chemoresistance. The purpose of this study is therefore to evaluate the efficacy of risk factors in predicting single-agent chemoresistance and explore the feasibility of simplifying the FIGO 2000 scoring system for GTN.

The clinical data of 578 GTN patients who received chemotherapy between January 2000 and December 2018 were retrospectively reviewed. Univariate and multivariate logistic regression analyses were carried out to identify risk factors associated with single-agent chemoresistance in low-risk GTN patients. Then, simplified models were built and compared with the original FIGO 2000 scoring system.

Among the eight FIGO risk factors, the univariate and multivariate analyses identified that pretreatment serum human chorionic gonadotropin (hCG) level and interval from antecedent pregnancy were consistently independent predictors for both first-line and subsequent single-agent chemoresistance. The simplified model with two independent factors showed a better performance in predicting single-agent chemoresistance than the model with the other four non-independent factors. However, the addition of other co-factors did improve the efficiency. Overall, simplified models can achieve favorable performance, but the original FIGO 2000 prognostic system still features the highest discrimination.

Pretreatment serum hCG level and interval from antecedent pregnancy were independent predictors for both first-line and subsequent single-agent chemoresistance, and they had greater weight than other non-independent factors in predicting single-agent chemoresistance. The simplified model composed of certain selected factors is a promising alternative to the original FIGO 2000 prognostic system, and it shows comparable performance.