Efficacy and Risk Factors Associated to Resistance to Single-Agent Chemotherapy in Low-Risk Gestational Trophoblastic Neoplasia

Objectives: This study aimed to assess efficacy of intramuscular methotrexate 8-day protocol in the treatment of low-risk gestational trophoblastic neoplasia and also identify prognostic factors associated with treatment failure, necessitating second line chemotherapy. Methods: This study was performed at Gynaecologic and Obstetric Clinic of Dakar Teaching Hospital, the reference Centre of Gestational Trophoblastic Disease in Senegal. At the beginning of 2011, patients were followed according to FIGO’s recommendations. From 2011 to 2014, we diagnosed 88 low-risk gestational trophoblastic neoplasia (GTN) patients (WHO score < 7). Low-risk patients started their treatment with methotrexate (MTX) based on the 8-day protocol consisting of 1 mg/kg MTX in combination with 0.1 mg/kg folinic acid (FA) every other day. Resistance to treatment was the main outcome. We studied the association of different prognostic factors included in the World Health Organisation (WHO) scoring system and resistance to the initial single agent chemotherapy. Results: Eighty-eight patients were diagnosed for GTN during the study period. Average age was 31 years. The antecedent pregnancy was molar in 98.1% of cases. Seventy-four patients underwent remission after single agent-chemotherapy. Resistance rate to single-agent chemotherapy was 15.9% (14 patients). Nine of them achieved remission after second line chemotherapy. WHO score was significantly associated with the risk of resistance to single-agent chemotherapy. Other variables included in the WHO as age, antecedent pregnancy, pre-treatment hCG, tumour size and FIGO stage were not significantly associated with resistance. We report five fatal cases. Conclusion: The 8-day protocol consisting of 1 mg/kg MTX in combination with 0.1 mg/kg folinic acid (FA) every other day is effective for women with LRGTN. The only significant prognostic factor for failure is pretreatment WHO score. We highly recommend the use of this protocol particularly in developing countries where methotrexate is available, affordable and relatively safe.