Phase III, Multicenter, Randomized Trial of Maintenance Chemotherapy Versus Observation in Patients With Metastatic Breast Cancer After Achieving Disease Control With Six Cycles of Gemcitabine Plus Paclitaxel As First-Line Chemotherapy: KCSG-BR07-02

PURPOSE: The primary purpose of our study was to evaluate whether maintenance chemotherapy with paclitaxel/gemcitabine (PG) was superior to observation in improving progression-free survival (PFS) in patients with metastatic breast cancer (MBC) who achieved disease control with an initial six cycles of PG as their first-line treatment. PATIENTS AND METHODS: The study was a prospective, randomized, multicenter, phase III trial. Patients MBC with who achieved disease control after six cycles of PG chemotherapy were randomly assigned to maintenance chemotherapy or observation until progression. RESULTS: Of 324 patients from 10 centers enrolled, 231 patients with MBC exhibited disease control (complete response + partial response + stable disease) with first-line PG and were randomly assigned to maintenance chemotherapy (n = 116) or observation (n = 115). The median age was 48 years (range, 28 to 76 years), median follow-up was 33 months, and median number of chemotherapy cycles in the maintenance group after random assignment was six. The median PFS time after random assignment was longer in the maintenance group than in the observation group (7.5 v 3.8 months, respectively; P = .026). The median overall survival (OS) time was longer in the maintenance group than in the observation group (32.3 v 23.5 months, respectively; P = .047). The rate of grade 3 or higher neutropenia after random assignment was higher in the maintenance group than in the observation group (61% v 0.9%, respectively; P < .001). CONCLUSION: In patients with MBC who achieved disease control with an initial six cycles of PG chemotherapy, maintenance PG chemotherapy resulted in better PFS and OS compared with observation.