What is known and objective: Chemotherapy is the primary pharmacotherapy of triple-negative breast cancer (TNBC). But the benefit of adjuvant chemotherapy in the oldest old TNBC patients remains controversial. Hence, we designed this population based observational study in order to assess the survival benefit of adjuvant chemotherapy in oldest old TNBC patients with early-stage disease.Methods: TNBC patients aged 80 years and older that with stage I to III invasive disease were identified in the surveillance, epidemiology, and end results cancer database from 2010 to 2016.Results and discussion: Of 1611 patients enrolled, 1356 (84.17%) did not receive chemotherapy. Age, race, histology, grade, T stage, N stage, and radiation were found to be strong predictors of chemotherapy recipient by multivariate logistic regression analysis. Chemotherapy significantly prolonged overall survival (OS) (HR, 0.62, 95% CI: 0.49-0.79, p < 0.001), but did not significantly reduce breast cancer specific death (BCSD) (HR, 0.92, 95% CI: 0.63-1.35, p = 0.675). These results were further confirmed by propensity score matching analysis. Chemotherapy was associated with better OS in the subgroup of patients aged 80-84 years old (HR, 0.54, 95% CI: 0.40-0.74, p < 0.001), T2-4 stage disease (HR, 0.58, 95% CI: 0.44-0.76, p < 0.001), or grade 3-4 disease (HR, 0.54, 95% CI: 0.41-0.71, p < 0.001). However, chemotherapy did not reduce the cumulative incidence of BCSD in any subgroup.What is new and conclusion: Chemotherapy should be considered for TNBC patients aged 80-84 years old, T2-4 disease, or grade 3-4 disease.
