Sentinel lymph node biopsy after neoadjuvant chemotherapy is accurate in breast cancer patients with a clinically negative axillary nodal status at presentation

Background: In breast cancer, neoadjuvant chemotherapy (NAC) is widely used in order to enable a conservative surgery. In patients treated with NAC, the use of sentinel lymph node (SLN) biopsy, which is a good predictor of the axillary nodal status in previously untreated patients, is still discussed. The aim of our study was to determine clinicopathological factors that may influence the accuracy of SLN biopsy after NAC. Methods: Between March 2001 and December 2006, 129 patients with infiltrating breast carcinoma were studied prospectively. Preoperatively, all of them underwent NAC. At surgery, SLN biopsy followed by axillary lymph node (ALN) dissection was performed. Lymphatic mapping was done using the isotope method. Results: The SLN identification rate was 93.8% (121/129). Fifty-six out of the 121 successfully mapped patients had positive ALN. Eight out of these 56 patients had tumor-free SLN (false-negative rate of 14.3%). The false-negative rate was correlated with larger tumor size (T1-T2 versus T3; P = 0.045) and positive clinical nodal status (N0 versus N1-N2; P = 0.003) before NAC. In particular, the false-negative rate was 0% (0/29) in N0 patients and 29.6% (8/27) in N1-N2 patients. Clinical and pathological responses to NAC did not influence the accuracy of SLN biopsy. Conclusions: Our results show that clinical nodal status is the main clinicopathological factor influencing the false-negative rate of SLN biopsy after NAC for breast cancer. SLN biopsy after NAC can predict the ALN status with a high accuracy in patients who are clinically lymph node negative at presentation.