Additional Axillary Disease After Neoadjuvant Chemotherapy for Patients with Clinically Node-Negative but Sentinel Node-Positive Disease.

Background: Axillary lymph node dissection (ALND) is associated with considerable risk of arm morbidity. This study aimed to identify risk factors for additional disease found at ALND in patients with a diagnosis of clinically node-negative (cN0) breast cancer who had sentinel lymph node (SLN) metastasis after neoadjuvant chemotherapy (NACT) as a help to identify patients for whom ALND may be safely omitted.

Methods: This retrospective national cohort study analyzed Danish patients with a diagnosis of cT1-3 breast cancer and cN0 disease from October 2016 to November 2022 but a positive SLN biopsy after NACT. Uni- and multivariable logistic regression analyses with stepwise backward elimination were performed to identify factors predictive of additional axillary disease at ALND.

Results: The study identified 346 patients eligible for analyses. Additional disease at ALND was found in 111 patients (32 %), but only 11 % of those with isolated tumor cells in the SLNs had additional axillary disease. It was respectively 22 % and 42 % for micro- and macrometastases. The final multivariable model identified the size of the metastatic deposit in the SLN, the ratio of positive SLNs, extracapsular extension, multifocality, and clinical T-stage as significant predictors of additional axillary disease.

Conclusion: Patients with isolated tumor cells in the sentinel nodes after NACT have a limited risk of additional axillary disease at ALND. However, other factors influence the probability and may be considered in an individualized approach.