Low-risk gestational trophoblastic neoplasia and methotrexate resistance: predictors of response to treatment with actinomycin D and need for combination chemotherapy.

Objective: To determine whether any clinical parameters predict the need for multiagent chemotherapy for treatment of low-risk gestational trophoblastic neoplasia (GTN) after the development of methotrexate (MTX) resistance.

Study Design: We retrospectively analyzed clinical data from the New England Trophoblastic Disease Center from women with post-molar GTN between 1973 and 2003.

Results: We analyzed data from 150 women (40 with partial mole, 110 with complete mole) who received single-agent MTX for low-risk GTN using FIGO and WHO scoring systems. Of the 45 women who developed MTX resistance, the majority (37/45) of these patients received actinomycin D, with 10 patients ultimately requiring multiagent chemotherapy. The requirement for multiagent chemotherapy following MTX resistance was associated with a beta-hCG > 600 mlU/mL 1 week following initial MTX therapy (p < 0.03). Conversely, a beta-hCG < 600 mlU/mL 1 week following initial MTX therapy was as-sociated with a 93% probability of remission with actinomycin D alone. All patients went into durable remission.

Conclusion: The prognosis for patients with low-risk GTN following molar gestation is excellent, with 100% remission rate, though a small but significant proportion (7%) required multiagent chemotherapy. The need for multiagent chemotherapy was associated with beta-hCG levels 1 week following initial MTX therapy.