Sentinel node biopsy after neoadjuvant treatment in breast cancer : five-year follow-up of patients with clinically node-negative or node-positive disease before treatment

Purpose: It is controversial whether sentinel node biopsy (SNB) without axillary dissection (AD) should be performed in cN1/2 breast cancer patients who become cN0 after neoadjuvant treatment, since the false negative rate (FNR) may be unacceptably high. We assessed outcomes to address this issue. Methods: We retrospectively assessed 396 cT1-4, cN0/1/2 patients, who became or remained cN0 after neoadjuvant treatment and underwent SNB with at least one sentinel node (SN) found, and AD not performed if the SN was negative. Results: After a median follow-up of 61 months (interquartile range 38-82), five-year overall survival was 90.7% (95%CI, 87.7-93.7) in the whole cohort, 93.3% (95%CI, 90.0-96.6) in those initially cN0, and 86.3% (95%CI, 80.6-92.1) in those initially cN1/2 (P = 0.12). Axillary failure occurred in only 1 (0.7%) initially cN1/2 patient who became cN0. In initially cN0 patients, and also initially cN1/2 patients who responded well to neoadjuvant treatment (ypT0/ypTx), SN-negativity was a significant predictor of good outcome, consistent with the known prognostic significance of axillary status, and suggesting that SN status accurately reflected axillary status. By contrast, in initially cN1/2 patients found to be ypT1/2/3, SN status (and whether or not AD was performed) had no influence on survival. Conclusions: These findings suggest that SNB is acceptable in cN1/2 patients who become cN0 after neoadjuvant therapy.