Accuracy of Touch Preparation versus Frozen Section for Intraoperative Diagnosis of Sentinel Lymph Node Metastases in Breast Cancer with Emphasis on Micrometastases

Abstract

The sensitivity of intraoperative diagnosis of sentinel lymph node (SLN) metastases in breast cancer is variably low. The purpose of this study was to review the pros and cons of frozen section (FS) and touch preparation (TP) methods, particularly in micrometastases. Intraoperative TP or FS was performed on the SLN of consecutive breast cancer patients from 2007 to 2009. Sensitivity, specificity, and overall accuracy of detecting positive SLNs were calculated for FS and TP groups. There were 396 patients with SLN biopsy. 124 (31.3 %) patients had at least one positive SLN. A total of 1270 lymph nodes were examined intraoperatively, 133 with FS and 1137 with TP. FS was significantly more sensitive than TP, 82.6% and 49.6%, respectively (p<0.0001). There were a total of 57 SLNs with micrometastases. FS was performed on 10 and TP on 47. The sensitivity of FS was 50% and for TP, 19.3% (p<0.0001). Of the 10 positive SLNs using FS, 3 were negative on permanent sections (PS). We conclude that FS is superior to TP as a method of detecting micrometastases in SLNs. However, a significant subset of patients who had positive SLNs on FS became negative on PS.  This raises the possibility that some negative SLNs on FS might have been understaged.