Outcomes for relapsed versus resistant low risk gestational trophoblastic neoplasia following single-agent chemotherapy.

OBJECTIVE: To compare outcomes for relapsed versus resistant low risk gestational trophoblastic neoplasia (GTN) following single-agent chemotherapy. METHODS: This was a single center retrospective study of low risk GTN. Cases failing to achieve a normal hCG with first-line therapy were defined as chemotherapy resistance. Cases achieving hCG remission, but recurring, were defined as relapse. Primary endpoints were remission rate with second-line therapy and time to remission. Univariate and multivariate analyses were performed to define prognostic factors. RESULTS: Among 877 low risk GTN patients there were 124 (14.8%) chemotherapy resistant and 22 (2.6%) relapse cases. Complete remission rates with second-line therapy were similar between relapse (77.3%) and resistant (76.6%) cases (p = 0.95), but resistance was associated with a longer time to reach complete remission with second-line therapy (median 8.3 vs 4.9 weeks; p = 0.024). In multivariate analysis, the significant prognostic factors for second-line therapy remission and time to second-line therapy remission were use of multi-agent chemotherapy (OR of 9.45; 95%CI, 2.13-41.97; p = 0.003) and primary chemo-resistance (HR of 0.27; 95%CI, 0.12-0.59; p = 0.001), respectively. With additional therapies, sustained remission rates rose to 90% (18/20) for relapse and 99.2% (120/121) for chemo-resistance (p = 0.053). CONCLUSIONS: Although second-line therapy for resistant or relapsed low risk GTN is able to achieve complete remission in most cases, time to complete remission for relapsed disease was shorter than for resistant disease. Further studies on the biologic differences between resistant and relapsed disease may clarify the optimal treatment for these clinical situations.