Background: Frozen-section analysis (FS) of the sentinel lymph node (SLN) is performed to avoid reoperation for axillary lymph node dissection (ALND), but it can miss micrometastatic disease, is labor intensive for the pathologist, and does not alter the number of breast-conservation therapy (BCT) patients needing reoperation for positive margins. The purpose of this study was to determine if eliminating FS would change reoperation rates in BCT patients. Study Design: Between January 2004 and December 2005, 1,218 patients had simultaneous BCT and SLN biopsy for invasive breast cancer. FS of the SLN was used selectively at the surgeon's discretion. Clinical and pathologic data were collected. Results: Overall, 542 of 1,218 (44%) patients had positive margins. FS of the SLN was performed in 931 of 1,218 (76%) patients. In those having FS, the SLN positivity rate was 33% (306 of 931). FS identified the positive SLN in 170 of 306 (56%) patients with positive nodes, allowing for immediate ALND. But 101 of these 170 patients had positive lumpectomy margins; and FS of the SLN saved 69 of 931 (7%) patients a second operation. Of patients not having FS, 48 of 287 (17%) had a positive SLN on final pathology. Only 18 of 48 (those seen on routine hematoxylin and eosin) might have been seen on FS, potentially sparing reoperation. Half of patients not having FS required reexcision for positive margins. FS would have spared reoperation for only 8 of 287 (3%) patients in this group. Overall, of 354 of 1,218 patients with SLN metastases, 170 had immediate ALND and 98 had delayed ALND. Of those having delayed ALND, 68 of 98 also had positive margins. Conclusions: Among patients having BCT with SLN biopsy, FS identified the positive SLN in 56% of patients with positive SLNs, allowing immediate ALND, and was false negative in 44%. Margin status remains a frequent indication for reoperation in BCT; routine FS analysis of the SLN ultimately saves only a minority of patients a second operation.
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