en Oncology Oncology Original Article Original Article <div style="text-align: justify;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background</span></i></b><i><span style="color:blue">:</span></i> <span lang="EN">Methotrexate (MTX) and actinomycin D (ActD) have been used as first-line chemotherapy agents in the treatment of low-risk gestational trophoblastic neoplasia (GTN). Although low-risk GTN is considered a curable disease, its reported primary remission rates of 49 to 93% reflect the difficulties of treatment and different factors influencing it. Hence, this study aimed to determine the remission rates and related factors of single-agent chemotherapy resistance in low-risk GTN patients.</span><span style="font-size:9.0pt"></span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods:</span></i></b> <span lang="EN">This retrospective study included patients with diagnosed low-risk GTN who received either MTX once a week (IM, 30mg/m2) or ActD once every two weeks (pulsed IV, 1.25mg/m2). Then, the patients were followed-up until complete remission or single-agent treatment failure to assess resistance rate and related factors. </span>&nbsp;<span style="font-size:10.0pt"></span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results:</span></i></b> <span lang="EN">Eighty-four patients were included in the study (18 patients were receiving MTX and 66 patients were receiving ActD). 85.7% of all participants achieved complete remission after first-line chemotherapy (72.2% in MTX vs 89.4% in ActD). There was a significant association for higher tumor size (P=0.046), the occurrence of metastasis (P=0.019), and pretreatment &beta;-HCG levels (P=0.005) with resistance to treatment.</span><b><i><span style="color:blue"></span></i></b></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion</span></i></b><i><span style="color:blue">:</span></i> <span lang="EN">This study demonstrated higher tumor size, the occurrence of metastasis, and pretreatment &beta;-HCG levels have been associated with increased resistance to first-line chemotherapy agents.</span><b><i><span style="color:#0033cc"></span></i></b></span></span></span></div> Single-agent chemotherapy, Gestational trophoblastic neoplasia, Dactinomycin, Methotrexate, Treatment failure 47 52 http://caspjim.com/browse.php?a_code=A-10-2332-3&slc_lang=en&sid=1 Shahrzad Sheikhhasani dr_sh1356@yahoo.com 100319475328460040799 100319475328460040799 No Department of Oncologic Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran Aghdas Abdolrazaghnejad dr.abdolrazaghnejad.gynecologist@gmail.com 100319475328460040800 100319475328460040800 Yes Department of Oncologic Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran Azam sadat Mousavi Azamsadat_mousavi@yahoo.com 100319475328460040801 100319475328460040801 No Department of Oncologic Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran Setareh Akhavan Setare_akh@yahoo.com 100319475328460040802 100319475328460040802 No Department of Oncologic Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran Narges Zamani dr.narges.zamani@gmail.com 100319475328460040803 100319475328460040803 No Department of Oncologic Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran Elham Feizabad elhamfeizabad@gmail.com 100319475328460040804 100319475328460040804 No Department of Oncologic Gynecology, Vali-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran