Clinical significance of MSKCC nomogram on guiding the application of touch imprint cytology and frozen section in intraoperative assessment of breast sentinel lymph nodes

Abstract

The widely practiced intra-operative methods for rapid evaluation and detection of sentinel lymph node (SLN) status include frozen section (FS) and touch imprint cytology (TIC). This study optimized the use of TIC and FS in the intra-operative detection of breast SLNs based on the Memorial Sloan Kettering Cancer Center (MSKCC) nomogram. Three hundred forty-two SLNs were removed from 79 patients. SLN metastatic probability was assessed by the MSKCC nomogram. The SLNs underwent intra-operative TIC and FS, as well as routine post-operative paraffin sections (RPSs). The relationships between TIC, FS, and SLN metastatic probability were analyzed. Overall, TIC was more sensitive than FS (92.31% vs. 76.92%), while TIC specificity was inferior to FS specificity (84.85% vs. 100%). In addition, the best cut-off value for TIC based on the MSKCC nomogram was inferior to the best FS cut-off value (22.5% vs. 34.5%). All patients with a MSKCC value <22.5% in the present study were negative based on FS and RPS, while the true-negative and false-positive rates for TIC were 92.5% and 7.5%, respectively. Thus, early breast cancer patients, based on a MSKCC value <22.5%, can safely avoid FS, but should have TIC performed intra-operatively. Patients with a MSKCC value >22.5% should have TIC and FS to determine the size of metastases, whether or not to proceed with axillary lymph node dissection, and to avoid easily missed metastases.

Keywords: Memorial Sloan Kettering Cancer Center nomogram; early breast cancer; frozen section; intraoperative detection; touch imprint cytology.

Figure 1. Representative photomicrographs of TIC staining of SLNs

A. A ‘true-positive’ sentinel lymph node that was positive with both intra-operative TIC and post-operative RPS (H&E; magnification, ×200); B. A ‘true-negative’ sentinel lymph node that was negative with both intra-operative TIC and post-operative RPS (H&E; magnification, ×200); C. A ‘false-positive’ sentinel lymph node that was positive with TIC, but negative with RPS (H&E; magnification, ×400).

Figure 2. The relationship of TIC, FS, and SLNs metastatic risk predicted by the MSKCC nomogram

A. MSKCC predicted SLN metastatic risk ranges of TIC(-)FS(-), TIC(+)FS(-), and TIC(+)FS(+) [95% CI]. B. The ROC curve of MSKCC prediction for TIC. C. The ROC curve of MSKCC prediction for FS.