INTRODUCTION

Patients with early-stage triple-negative breast cancer (TNBC) have a higher risk of distant recurrence and death compared to patients with other breast cancer subtypes, including patients with small tumors1. Currently, adjuvant chemotherapy is the mainstay of systemic therapy for patients with stage I TNBC, who represent approximately one-third of TNBC patients.2 Among patients with stage IA TNBC (i.e., tumors ≤2 cm and node-negative), the National Comprehensive Cancer Network guidelines recommend adjuvant chemotherapy for tumors 1.1–2 cm (T1c), with consideration of adjuvant chemotherapy for tumors 0.6–1 cm (T1b). Patients with tumors ≤0.5 cm (T1a) are not recommended to receive adjuvant chemotherapy2,3. However, the utilization and benefit of chemotherapy for this population in the modern era remain poorly defined.

We conducted a population-based study using Surveillance, Epidemiology, and End Results (SEER) to investigate adjuvant chemotherapy treatment patterns and survival outcomes among patients diagnosed with stage IA TNBC between 2010 and 2019. We included 8601 women diagnosed with stage IA TNBC between 2010 and 2019. Patient demographics and disease information are included in Table 1. The median age at diagnosis was 62 years old. Most patients (92.79%) had invasive ductal carcinomas, T1c disease (60.85%) and grade 3 (i.e., high-grade) tumors (70.14%). Adjuvant chemotherapy was administered to 5295 patients (61.6%). Median follow-up for survival analyses was 48 months (interquartile range: 20–83 months).