Relapse Rate of Patients with Low-Risk Gestational Trophoblastic Tumor Initially Treated With Single-Agent Chemotherapy

Abstract

The authors studied all patients with low-risk gestational trophoblastic tumor who were treated with single-agent chemotherapy at their institution between 1974 and 2000. Their aim was to compare remission rates among these 272 patients and to identify risk factors for development of drug resistance or disease relapse. Chemotherapy agents included conventional methotrexate (MTX), MTX with folinic acid (MTZ-CF), actinomycin D (Act-D), or etoposide. Primary remission according to chemotherapy regimen was 91 of 133 (68.4%) among those receiving MTX, 14 of 24 (58.3%) in those treated with MTX-CF, 20 of 24 (58.3%) for Act-D, and 81 of 89 (91%) in the etoposide group. The primary remission rate was significantly higher in patients who received etoposide compared to MTX (P < 0.0001) or MTX-CF (P = 0.0005). Overall, 24 patients (8.8%) developed drug resistance, including 10 (7.5%) MTX patients, 6 (25%) in the MTX-CF group, 4 (15.4%) Act-D patients, and 4 (4.5%) etoposide patients. Drug resistance was significantly higher for MTX-CF patients compared with etoposide patients (P =.006). Twenty (83.3%) of these 24 patients achieved remission with the second-line chemotherapy. The remaining 4 developed resistance to the second-line drug and required combination chemotherapy to achieve remission. Forty-two patients (15.4%) required a change of chemotherapy as a result of drug toxicity. Toxicity developed in 32 (24.1%) MTX patients, 4 (16.7%) MTX-CF patients, 2 (7.7%) Act-D patients, and 4 (4.5%) etoposide patients. The toxicity rate was significantly higher for MTX compared with etoposide (P < 0.0001). Only one of these 42 patients failed to achieve remission with second-line single-agent chemotherapy and required third-line treatment for successful remission. In an analysis of risk factors for drug resistance, including pretreatment hCG titers, chemotherapy with hysterectomy, disease metastasis, patient age, and initial FIGO scores, only higher FIGO scores were significantly associated with drug resistance (P = 0.026). Of the 230 patients who achieved primary remission, 6 (2.6%) developed a recurrence of disease. Relapse was not associated with chemotherapy agent, hCG titers, hysterectomy with treatment, metastases, or maternal age. However, relapse rates were higher among the patients who became drug-resistant (P = 0.016). Also, higher FIGO scores were significantly associated with relapse (P = 0.016).