The effect of prophylactic chemotherapy on treatment outcome of postmolar gestational trophoblastic neoplasia

Background: Prophylactic chemotherapy (P-chem) was considered as an effective method to prevent malignant transformation of high-risk HM. However, P-chem might increase the risk of subsequent drug resistance and delay the time to diagnosis of gestational trophoblastic neoplasia (GTN). The objective of this study was to evaluate whether P-chem increased the drug resistance rate of postmolar GTN and whether the first-line chemotherapy of low-risk GTN after P-chem should be different from P-chem. Methods: : Postmolar GTN were divided into P-Chem group and control group, according to whether they received P-Chem. The control group and P-Chem group were matched according to age, high-risk/low-risk GTN. Postmolar GTN patients without P-chem were randomly selected as the control group at 3:1. The clinical parameters of these patients were collected and compared. Results: : Totally 455 low-risk and 32 high-risk postmolar GTN patients were treated at our hospital between 2008.01.01 and 2017.12.31. WHO risk score, chemotherapy cycles to achieve hCG normalization and resistant rate were similar between P-chem (27 cases) and control (81 cases) group, no matter in low-risk or high-risk GTN. Among low-risk GTN patients, interval from hydatidiform mole to GTN was significantly longer in P-chem group than control (44 vs 69 days, P=0.001). Total chemotherapy cycles and resistant rate were similar between low-risk GTN treated with same agent as P-chem (group A) and alternative agent (group B). But group A needed more chemotherapy cycles to achieve hCG normalization than group B, no matter in all 24 GTN received P-chem (4.4 vs 2.8, p=0.024) or in 22 GTN received methotrexate as P-chem (3 vs 2, p=0.004). Conclusions: : P-chem delayed the time to GTN diagnosis, but didn’t increase risk score or lead to drug resistance of postmolar GTN. Alternative agent different from P-chem had the potential of increasing chemotherapy response in low- risk postmolar GTN.