Sentinel Node Biopsy alone or with Axillary Dissection in Breast Cancer Patients after Primary Chemotherapy: Long-term Results of a Prospective Interventional Study.

OBJECTIVE To ascertain, in cN0/1 breast cancer patients given primary chemotherapy followed by sentinel node biopsy (SNB), whether SNB alone is adequate axillary treatment if the sentinel nodes (SNs) are clear (pN0). SUMMARY BACKGROUND DATA 2020 guidelines do not recommend SNB in most cN1 patients with clear SNs after primary chemotherapy because the high SNB false negative rate might lead to poorer outcomes. METHODS We prospectively assigned SNB after primary chemotherapy to 353 consecutive cT2 cN0/1 patients, median age 47 years (range 22-76) treated from 2007 to 2015. If the SNs were pN0, patients generally received no further axillary treatment (SNB only); if the SNs were pN1, completion AD (SNB + AD) was usually performed. Primary outcomes were overall (OS) and disease-free (DFS) survival in SNB only vs SNB + AD patients, assessed by Kaplan-Meier and compared using log-rank test, with use of propensity scores to account for bias due to non-random assignment to SNB vs SNB + AD. RESULTS Median follow-up was 108 months, interquartile range 66-136. OS and DFS did not differ significantly between the groups by propensity score-weighted comparison: 10-year OS 89% (95%CI: 81-99%) in SNB only patients vs 86% (95%CI: 78-95%) in SNB + AD patients; 10-year DFS 79% (95%CI: 68-92%) vs 69% (95%CI: 58-81%). No SNB-only patient developed axillary failure. CONCLUSIONS cT2 cN0/1 patients whose SNs are disease-free (pN0) after primary chemotherapy can be offered SNB (with no further axillary treatment if the SNs are negative), irrespective of axillary status beforehand, without affecting OS or DFS.