Materials and Methods: This retrospective cohort study reviewed the medical records of 272 patients with the definitive diagnosis of GTN referring to Imam Khomeini hospital in Tehran during 2007-2017.

Results: The mean age of participants was 29.19 ± 7.46 years. The abnormal uterine bleeding (AUB) was the most common clinical manifestation in 64.3% of patients. Regarding the risk scoring condition according to the World Health Organization criteria, 77.6%, 9.1%, and 13.3% were categorized as low-, intermediate-, and high-risk cases. Single therapy with methotrexate was used in 22.8% of patients and actinomycin-D was planned for 42.3% whereas 11.0% and 1.5% were considered for treatment with the EMA-CO (Etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine) and EMA-EP (Etoposide methotrexate and actinomycin-D/etoposide and cisplatin) regimens, respectively. Good response to methotrexate was 66.7% but it was 83.6% in the ACT group (P = 0.001). The resistance to single-agent chemotherapy in low- and intermediate-risk groups was 16% and 92%, respectively. In addition, 20.2% of patients in stage one had tumor invasion pattern in the uterus in pretreatment Doppler ultrasonography, but 52% and 30% had resistance to chemotherapy treatment in invasive and noninvasive groups, respectively (P = 0.008).

Conclusions: In general, due to the high resistance of the intermediate-risk subgroup to a single therapy, a combination therapy may be more useful to treat this disorder. The close association between tumor invasion pattern in the uterus in Doppler ultrasonography and drug resistance can be considered as a new criterion for tumor risk scoring.