Histologic detection and clinical implications of micrometastases in axillary sentinel lymph nodes for patients with breast carcinoma

BACKGROUND. Sentinel lymph node (SLN) biopsy is used increasingly in patien ts with clinically lymph node negative, early-stage breast carcinoma, becau se it can spare axillary dissection when the sentinel lymph nodes are negat ive. The question arises, however, whether complete axillary lymph node dis section (ALND) also is necessary in patients with only micrometastases (les s than or equal to 2 mm in greatest dimension) in axillary SLNs. The author s carried out the current study to ascertain the risk of non-SLN axillary m etastases in such patients and to assess the detection rate of SLN micromet astases in relation to the sectioning interval and the number of. sections examined. METHODS. The authors examined 109 patients with micrometastatic SLNs from a series of 634 patients with carcinoma of the breast who underwent SLN biop sy and complete ALND as part of the surgical treatment for their disease. T he SLNs were sectioned completely at 50-mum intervals, and the sections wer e examined intraoperatively. RESULTS. The overall frequency of metastases in axillary non-SLNs was 21.8% . The frequency was correlated significantly with the size of the SLN micro metastatic focus (P = 0.02): 36.4% of patients with foci > I mm had metasta ses in axillary lymph nodes-a percentage approaching 44.7% of patients with macrometastatic SLNs-whereas only 15.6% of patients with micrometastases l ess than or equal to 1 mm had other involved axillary lymph nodes. CONCLUSIONS. Outside of clinical trials, patients with TI and small T2 brea st carcinoma and micrometastatic SLNs should undergo complete ALND for adeq uate staging. However, patients with SLN micrometastases up to I mm in grea test dimension have a significantly lower risk of additional axillary metas tases, raising the question of whether ALND may be avoided in this subgroup of patients. (C) 2001 American Cancer Society.