The utility of intraoperative evaluation of sentinel lymph nodes in breast cancer.

Background: In breast cancer treatment, intraoperative sentinel lymph node (SLN) evaluation is used to identify patients who may potentially benefit from immediate completion of axillary lymph node dissection.

Methods: Prospectively collected breast cancer registry data identified 516 SLN biopsies between January 2003 and December 2005. Intraoperative evaluation (IE) of the SLNs was performed in 479 axillae. Final pathology by hematoxylin and eosin and, for negative nodes, by immunohistochemical stains was compared with the IE result. The effect of IE and final pathology on surgical treatment was examined.

Results: The sensitivities for IE of N0(i+) (n = 39), N1mi (n = 41), and N1a-3a (n = 89) metastases were 0%, 5%, and 63%, respectively. The specificity was 99.7%. IE identified 57 (44%) of SLN-positive (N1mi and N1a-3a) axillae, thus resulting in synchronous axillary lymph node dissection for those patients. Reoperation for false-negative IEs (N1mi or N1a-3a with negative IE) occurred in only 27 axillae (39%).

Conclusions: IE of SLNs has adequate sensitivity and excellent specificity. In addition to allowing patients to benefit from synchronous surgery, IE helped patients to receive care in concordance with recommended practice guidelines. The false-negative IE of SLNs highlights uncertainty with the clinical significance of axillary nodal staging when only small amounts of metastatic disease are identified in the axilla.