Sentinel lymph node biopsy after neoadjuvant chemotherapy for breast cancer: retrospective comparative evaluation of clinically axillary lymph node positive and negative patients, including those with axillary lymph node metastases confirmed by fine needle aspiration

BACKGROUND: To evaluate the accuracy of sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) in breast cancer patients with axillary lymph node (ALN) metastasis. METHODS: A total of 122 patients with operable breast cancer were enrolled in this single-center retrospective study. Eighty patients were clinically diagnosed with a positive axillary lymph node (ALN) via imaging or physical examination (including 66 patients with biopsy-proven metastasis). The other 42 cases had a clinically negative ALN. After four sessions of neoadjuvant chemotherapy, patients were assigned to an ALN-positive or -negative group. The identification rate (IR) and false negative rate (FNR) were determined in the ALN-negative group. RESULTS: ALN changed from positive to negative after NAC in 48 patients. Among them, 46 had at least one SLN resected (total IR = 95.8 %). Eight of the 46 SLN-negative patients had pathologically confirmed metastasis of at least one non-SLN (FNR = 36 %). Fifty-five of the 56 patients with a biopsy-proven negative ALN remained ALN negative. Furthermore, 54 of the 56 patients had at least one SLN resected (IR =98.2 %). Three SLN-negative patients of the 54 had at least one positive non-SLN (FNR = 10.7 %). CONCLUSIONS: Due to its high FNR, post-NAC SLNB is not recommended for breast cancer patients with ALN metastasis confirmed by biopsy, though their ALN may become negative after NAC. However, for operable breast cancer with negative ALN, post-NAC SLNB is feasible if the ALN remains clinically negative after NAC. TRIAL REGISTRATION: Retrospective evaluation.