Study of Low-Risk GTN Patients Resistant to First-Line Chemotherapy with MTX in a Tertiary Hospital Center

Background & Objective: This study aimed to determine the response rate and related factors for resistance to single-agent chemotherapy in low-risk GTN patients.Materials & Methods: In a single-center retrospective descriptive study, all patients diagnosed with low-risk gestational trophoblastic neoplasia, referring to a tertiary hospital center in Mashhad, Iran, between 2013 and 2023, were included. Clinical data were extracted from the hospital registry system. Resistance to first-line single-agent chemotherapy was considered the primary result.Results: Out of 1015 cases of GTD, 135 cases of gestational trophoblastic neoplasia (13.3%) were recognized. 124(91.8%) patients were diagnosed with low-risk GTN. From low-risk GTN, 37(29.8%) patients received single-agent weekly methotrexate (50 mg/m2 IM), while 87(70.16%) patients received 8 days of MTX-folinic acid as first-line treatment. 48.6% (N=18/37) did not respond to weekly MTX, and 18.4) patients did not respond to eight days of MTX-folinic acid. All these patients receive second-line chemotherapy. 72.6% (n = 90/124) achieved a complete response on first-line chemotherapy, and 34(27.4%) patients received actinomycin-D in the second line. The mean B-HCG titer before administration of actinomycin-D for 73.5% (n=25/34) patients was 294.4 IU/ml. In the second line, a complete response was achieved in 76.47% (n=26) while 23.53% (n=8) of patients got 3rd-line chemotherapy. The complete response rate for all low-risk GTNs was 100%.Conclusion: Higher pretreatment serum hCG level, stage II-III, FIGO score 5-6, pathology Choriocarcinoma, and previous-term pregnancy were the risk factors of resistance to first-line chemotherapy with Methotrexate, highlighting the need for precise follow-up of patients with these criteria during the first line on single-agent chemotherapy.