Exploration of prognostic factors and the value of adjuvant chemotherapy in T1a,bN0M0 triple-negative breast cancer: a prospective cohort study based on the SEER database

Background: There are limited published studies on the prognostic predictors and the value of adjuvant chemotherapy (CT) in T1a,bN0M0 triple-negative breast cancer (TNBC) after local therapy. Therefore, the aim of the present study was to explore the prognostic predictors and the value of adjuvant CT in this population.Methods: We identified T1a,bN0M0 TNBC cases registered in the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015. We analyzed associations between patient characteristics and overall survival (OS) and breast cancer-specific mortality (BCSM), and differences in OS and BCSM in a CT and no chemotherapy (no CT) cohort before and after propensity score matching.Results: Of the 3,065 SEER patients, 1,534 (50.0%) received adjuvant CT. The median follow up was 57 months (interquartile range: 39-75 months). The 5-year OS and cumulative BCSM were 93.6% and 3.3%, respectively. Younger age was not associated with lower OS or higher BCSM in the total and no CT cohorts. Higher histologic grade was associated with lower OS in the no CT cohort, and T1b tumors were associated with higher BCSM in the total cohort. Multivariable analysis showed no association between adjuvant CT and OS or BCSM.Conclusions: Patients with T1a,bN0M0 TNBC had an excellent prognosis with or without adjuvant CT. For this population, higher histologic grade and larger tumor size were predictors of poor prognosis, although the effect of age was complex. Our data did not support using adjuvant CT in patients with