Effectiveness of adjuvant chemotherapy for elderly patients with triple-negative breast cancer

There is little evidence determining whether elderly patients (from 70 to 90 years old) with triple-negative breast cancer (TNBC) could benefit from adjuvant chemotherapy (AC). This study explores the effect of AC in these population following surgery. A total of 4610 patients were identified in the Surveillance, Epidemiology, and End Results database (2010-2018). Multiple imputation by chained equations was performed to impute missing data. Inverse probability of treatment weighting (IPTW) was applied to reduce the selection bias. IPTW-adjusted Kaplan-Meiers survival analysis and Cox proportional hazards models were performed to compare breast cancer-specific survival (BCSS) and overall survival (OS) in the two treatment groups. The patients were classified into the chemotherapy (n = 1989) and the observation (n = 2621) groups. The percentage of patients receiving AC vs observation increased significantly from 2010 to 2018 (estimated annual percentage change, 1.49%; 95%CI, 0.75-2.16%, p = 0.002). The 5-year IPTW-adjusted rates of BCSS and OS in the AC group were better than that in the observation group (BCSS: 82.32% vs 78.42%, p = 0.010; OS: 75.54% vs 64.65%, p < 0.001). The patients could benefit from AC based on the results of IPTW-adjusted Cox proportional hazards regression analysis (BCSS: HR, 0.77, 95%CI, 0.62-0.94, p = 0.012; OS: HR, 0.66, 95%CI, 0.57-0.78, p < 0.001). AC was associated with a significant outcome benefit across the year at diagnosis, marital status, stage, lymph node, surgery, and radiation subgroups (all p < 0.050). Patients with T1ab could not benefit from AC (p > 0.050). In conclusion, we presented a BCSS and OS benefit from AC in elderly patients with TNBC. AC remained a reasonable treatment approach in these specific patients. For the patients with T1ab, de-escalated treatment would be administrated with caution.