Sentinel Node Biopsy Alone Versus Sentinel Node Biopsy Plus Axillary Dissection in cT2 cN0/1 Breast Cancer After Neoadjuvant Chemotherapy: 15-Year Results of a Prospective Interventional Study.

[BACKGROUND] Recent guidelines recommend sentinel lymph node biopsy (SNB) of cN1 breast cancer when the axilla is clinically clear after neoadjuvant chemotherapy (NAC). It remains controversial whether further axillary treatment is required if the axillary sentinel nodes (SNs) are pN0.

[METHODS] This prospective non-randomized study analyzed 486 consecutive patients with cT2 cN0/1 breast cancer recruited from 2007 through 2021. Axillary status was assessed by palpation and ultrasound only. After NAC, patients who were cN0 underwent SNB. Those with negative SNs usually received no further axillary treatment, and those with involved SNs usually received AD. The primary end points were overall and disease-free survival for the SNB-only versus the SNB+AD patients, as estimated by the Kaplan-Meier method and log-rank test, with application of a propensity score because treatment assignment was not randomized.

[RESULTS] After a median follow-up of 102 months (interquartile range [IQR], 59-162 months) for the SNB-only patients and 200 months (IQR, 168-213 months) for the SNB+AD patients, overall and disease-free survival did not differ between the pN0 SNB-only and the pN0 SNB+AD patients. Furthermore, no SNB-only patient experienced axillary recurrence.

[CONCLUSIONS] For cT2 CN0/1 breast cancer patients who are cN0 after NAC, SNB can be offered, with no further axillary treatment if the SNs are negative, irrespective of axillary status beforehand, with no adverse effect on long-term outcomes.