Nodal Positivity in Early-Stage Triple-Negative Breast Cancer: Implications for Preoperative Immunotherapy

Adding pembrolizumab to preoperative chemotherapy improves event-free survival in patients with early-stage triple-negative breast cancer (TNBC). However, owing to potential toxicities, the risk-benefit ratio of pembrolizumab must be considered. There is consensus that the addition of immunotherapy should be recommended in node-positive patients. This study is undertaken to determine nodal positivity rates in patients with TNBC presenting with cT1-2N0 disease undergoing upfront surgery and to evaluate the utility of axillary ultrasound and biopsy in the setting of a negative clinical examination.

Patients with cT1-2N0 TNBC undergoing upfront surgery were identified from our institutional database (January 2016-February 2021; n = 343) and from the National Cancer Database (NCDB) (n = 46,015). Pathologic nodal status was determined. A second cohort of patients with cT1-T2 TNBC with a negative clinical examination was defined in our institutional database (n = 499), and utilization of axillary ultrasound was examined.

For patients undergoing upfront surgery, pathologically positive nodes were found in 14.6% patients of our institutional cohort: 9.4% cT1a/b, 14.9% cT1c, and 20.8% cT2 tumors. In the NCDB cohort, 13.7% patients were node positive: 4.9% cT1a/b, 11.4% cT1c, and 19.7% cT2 tumors. For patients with a normal clinical examination undergoing axillary ultrasound, 7.5% of cT1c and 8.7% of cT2 had suspicious nodes biopsied and confirmed positive for metastasis.

Pathologic node-positive disease is found in > 10 and 20% patients with cT1cN0 and cT2N0 TNBC, respectively. Axillary ultrasound can be used to identify patients presenting with a normal clinical examination for whom preoperative pembrolizumab should be considered.