Maintenance chemotherapy after 6 cycles of platinum-doublet regimen in anthracycline-and taxane-pretreated metastatic breast cancer

Background/Aims: Sequential monotherapy is recommended for anthracycline-and taxane-resistant metastatic breast cancer (MBC), but combination chemotherapy is considered in patients with visceral crisis. Cisplatin-doublet chemotherapy is a combination regimen for MBC, but prolonged treatment is challenging be-cause of toxicity. We analyzed the role of single-agent maintenance chemotherapy after cisplatin-doublet chemotherapy for MBC. Methods: From January 2011 to December 2017, 96 anthracycline-and taxane-resistant MBC patients were retrospectively reviewed, and 49 patients with a sustained clinical benefit during the initial 6 cycles of cisplatin-doublet chemotherapy were enrolled for study. Patients were treated with gemcitabine-cisplatin (gemcitabine, 1,250 mg/m², intravenously [IV], days 1 to 8; cisplatin 60 mg/m², IV, day 1) or capecitabine-cisplatin (capecitabine 2,500 mg/m², orally, days 1 to 14; cisplatin 60 mg/m², IV, day 1) during the induction period. After 6 cycles, 16 patients were switched to single-maintenance treatment (gemcitabine or capecitabine) and the doublet regimen was continued in 24 patients. Survival outcomes (progression-free survival [PFS] and overall survival [OS]) were analyzed. Results: Among the 49 patients who showed a clinical benefit during cispla-tin-doublet therapy, 24 were maintained on the doublet regimen, 16 were switched to single-maintenance treatment, and chemotherapy was suspended until disease progression in nine patients. The single-maintenance chemotherapy group showed superior survival than the chemotherapy holiday and doublet regimen groups (median PFS 15.43 months vs. 8.37 and 10.67 months, respectively, p = 0.008; median OS 43.67 months vs. 22.17 and 22.33 months, respectively, p = 0.014). Conclusions: Patients showing a clinical benefit during 6 cisplatin-doublet chemotherapy cycles may have a sustained survival benefit from single-maintenance chemotherapy.