Background: Platinum-based chemotherapy (PBCT) has gained an important position as a first-line treatment for metastatic triple-negative breast cancer (mTNBC). We assessed whether maintenance chemotherapy maintenance was superior to observation after first-line PBCT in patients with mTNBC.
Methods: A total of 265 patients with mTNBC who had exhibited non-PD after 4-6 cycles of firstline PBCT at the Fudan University Shanghai Cancer Center from January 2008 to April 2019 were retrospectively analyzed. 107 patients who did not receive additional treatment were defined as the control observation group, and the remaining 158 patients who continued to receive maintenance therapy were defined as the maintenance treatment group.
Results: The median progression-free survival (PFS) time in the maintenance group was 9.63 months, which was significantly longer than the PFS time of 7.47 months in the observation group (HR 0.49, 95% CI: 0.37-0.67, P<0.0001). The median overall survival (OS) of the observation group and the maintenance group was 25.37 months and 31.27 months, respectively (HR 0.65, 95% CI: 0.44-0.95, P=0.019). The survival benefit was still present after adjusting baseline characteristics. Moreover, multivariate analyses suggested that maintenance chemotherapy is an independent predictive factor for both PFS and OS. Interaction and stratified analyses showed no difference in the PFS with between the single-drug maintenance strategy, single agent or doublet group and the doublet-drug maintenance group. The most common adverse event in this study was hematologic toxicity. Except for hand-foot syndrome (0 vs. 7.6%, P=0.004), the incidence of other adverse events was not significantly different between the observation and maintenance groups.
Conclusions: After achieving non-PD with the first-line PBCT in mTNBC patients, chemotherapy maintenance may provide OS benefit prior to the era of biologicals.
Keywords: Metastatic breast cancer (MBC); maintenance therapy; platinums; triple-negative breast cancer (TNBC).