Correlation between outcome and extent of residual disease in the sentinel node after neoadjuvant chemotherapy in clinically fine-needle proven node-positive breast cancer patients

Background: Whether the extent of residual disease in the sentinel lymph node (SLN) after neoadjuvant chemotherapy (NAC) influences the prognosis in clinically node-positive breast cancer (BC) patients remains to be ascertained. Methods: One hundred and thirty-four consecutive cN+/BC-patients received NAC followed by SLN biopsy and axillary lymph node dissection. Cumulative incidence of overall (OS) and disease-free (DFS) survival, BC-related recurrences and death from BC were assessed using the Kaplan-Meier method both in the whole patient population and according to the SLN status. The log rank test was used for comparisons between groups. Results: The SLN was identified in 123/134 (91.8%) patients and was positive in 98/123 (79.7%) patients. Sixty-five of them (66.3%) had other axillary nodes involved. SLN sensitivity and false-negative rate were 88.0% and 2.0%, Median follow-up was 10.2 years. Ten-year cumulative incidence of axillary, breast and distant recurrences, and death from BC were 6.5%, 11.9%, 33.4% and 31.3%, respectively. Ten-year OS and DFS were 67.3% and 55.9%. When stratified by SLN status, 10-year cumulative incidence of BC-related and loco-regional events, and death from BC were similar between disease-free SLN and micrometastatic SLN subgroups (28.9% vs 30.2%, p = 0.954; 21.6% vs 13.4%, p = 0.840; 12.9 vs 24.5%, p=0.494). Likewise, 10-year OS and DFS were comparable (80.0% vs 75.5%, p=0.975 and 68.0% vs 69.8, p=0.836). Both OS and DFS were lower in patients presenting a macrometastatic SLN (60.2% and 47.5%). Conclusion: Outcome of patients with micrometastatic SLN was similar to that of patients with disease-free SLN, which was more favorable as compared to that of patients with macrometastatic SLN.