Increased false negative sentinel node biopsy rates after preoperative chemotherapy for invasive breast carcinoma.

BACKGROUND: Sentinel lymph node dissection (SLND) has been a promising new technique in breast carcinoma staging, but could be unreliable in certain patient subsets. The current study assessed whether age, preoperative chemotherapy, tumor size, and/or previous excisional biopsy influenced the identification of sentinel nodes (SLNs) or the reliability of a node-negative SLND in predicting a node negative axilla. METHODS: Eighty-two patients who had clinically negative axillae underwent SLND followed by Level I/II axillary lymph node dissection (ALND). SLNDs were performed using both technetium-99m (Tc-99m) labeled colloid and isosulfan blue dye. SLNs were analyzed by hematoxlyin and eosin and immunocytochemical techniques. RESULTS: SLNs were successfully identified in 80% of patients. Mapping success was decreased among postmenopausal women but was not influenced by preoperative chemotherapy, large tumor size, or previous excisional biopsy. Of the 31 successfully mapped, node positive patients, 5 had false negative (FN) SLNDs (overall FN rate = 16%). Of the 9 successfully mapped patients who had received preoperative chemotherapy and had positive axillary nodes, 3 had FN SLND (FN rate = 33%). The presence of clinically positive lymph nodes before chemotherapy did not predict which patients would have a subsequent FN SLND. T3 tumor size, but not previous excision, was associated significantly with increased FN rate, although the FN rate for previous excision was 11%. No FN SLND occurred with T1/T2 tumors that were not excised previously and had not received preoperative chemotherapy. CONCLUSIONS: Preoperative chemotherapy was associated with an unacceptably high FN rate for SLND. While larger tumor size also was associated with FN SLND, this effect might have been due to preoperative chemotherapy use in these patients. Small sample size precluded determining whether excisional biopsy before mapping increased FN SLND rates independently.