The role of single-dose prophylactic methotrexate in the prevention of post-molar gestational trophoblastic neoplasia in patients with high-risk molar pregnancy.

Introduction: Prophylactic chemotherapy (PC) has been suggested to be effective in prevention of post molar gestational trophoblastic neoplasia (PGTN) in patients with high-risk molar pregnancies. The goal of this study is to assess the efficacy of single dose methotrexate as PC in terms of spontaneous remission, time to remission, and progression to PGTN.

Materials and methods: Patients with molar pregnancy were recruited to the study and underwent cervical dilation and suction curettage. Patients who had pathologically proven complete hydatidiform mole were evaluated with abdominal ultrasonography to confirm complete evacuation and absence of remnants. These patients were allocated to two groups: group one received Methotrexate 50 mg/m2 via intramuscular injection, while group two did not. PGTN was defined according to the 2018 FIGO criteria. For patients with confirmed PGTN, the following variables were recorded: occurrence of metastasis, resistance to first-line chemotherapy and time to βHCG level normalization.

Results: Eighty patients were enrolled to the study, of which 22 cases (27.5%) received PC. It was found that PC with MTX did not significantly influence spontaneous remission (18 (81.8%) Vs 37 (63.7%), p value: 0.12) or time to remission (57 ± 22.5 Vs 61.24 ± 21.78 days, p value: 0.46) in high-risk molar pregnancies. Moreover, among patients in PC group and control group, 4 cases (18.2%) and 21 patients (36.3%) progressed to PGNT, respectively (p value: 0.12). Although patients in PC group tended to be diagnosed in lower stages compared to patients in control group, this difference was insignificance (p value: 0.95). Among patients who developed to PGTN, PC did not reduce the frequency of metastatic disease, resistance to first-line chemotherapy, or the time interval to serum βHCG level normalization (all p values > 0.05).

Conclusion: This study suggests that a single-dose MTX as PC may not be an effective therapeutic option for preventing PGTN in patients with high-risk molar pregnancy.