Background: Single-agent gemcitabine is a moderately effective compound in metastatic breast cancer (mBC) treatment. Carboplatin is frequently used in addition to gemcitabine to improve tumor responses, but with an unclear effect on survival outcomes. In this study we evaluated the antitumor efficacy and safety profiles of gemcitabine and carboplatin-gemcitabine in mBC patients.
Patients and methods: We retrospectively collected data on patients treated between April 2012 and February 2018 with gemcitabine 800 mg/m2or carboplatin at an area under the curve of 2 with gemcitabine 800 mg/m2, given on days 1 and 8 every 21 days. We compared progression-free survival (PFS), objective response rate (ORR), overall survival, and incidence of adverse events (AEs) in the 2 cohorts.
Results: Of 163 consecutive patients who met the inclusion criteria, 75 received gemcitabine and 88 carboplatin-gemcitabine. Patients in the combination cohort had received a lower number of previous chemotherapy lines (2 vs. 3), and were less likely to have received carboplatin (9 patients [10%] vs. 34 patients [45%]; P < .0001). We found no PFS differences in carboplatin-gemcitabine and gemcitabine cohorts (4.24 vs. 4.61 months; adjusted hazard ratio, 0.98; P = .92), whereas the combination was associated with a trend toward higher ORR (18 patients [20.4%] vs. 8 patients [10.6%]; P = .089) and with significantly higher incidence of Grade 3/4 neutropenia (30 patients [34%] vs. 5 patients [6.6%]; P < .0001).
Conclusion: Using carboplatin in addition to gemcitabine is associated with more hematologic AEs but not with better PFS. Although single-agent gemcitabine remains a treatment option for heavily pretreated mBC patients, finding biomarkers of response to platinum salts might help to identify patients more likely to benefit from carboplatin-gemcitabine.
Keywords: Adverse events; Metastatic breast cancer; Objective response rate; Overall survival; Progression-free survival.
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