Macroscopic Evaluation of the Trimmed Frozen Block Is a Helpful Tool for Intraoperative Assessment of Resection Margins of Breast Cancer Specimens

Introduction. The evaluation of the trimming surfaces (TS) of tissue blocks from frozen sections may serve as a supplementary examination tool for the intraoperative determination of resection margins of breast cancer specimens. This study aimed at the investigation of the feasibility and reliability of this technique, which has been described only very rarely in literature. Methods. Two observers assessed digital images from TS obtained from 57 resection margins. Findings were correlated with the diagnosis of the frozen section (FS) alone and the final diagnosis on formalin-fixed paraffin-embedded (FFPE) material. Results. The determination of the resection margin on TS was estimated as feasible for all cases. Interobserver congruence rate for TS was 96% (kappa = 0.81), which was lower compared with FFPE (100%, kappa = 1.0) but superior to FS (89%, kappa = 0.67). Intraobserver congruence of the 2 reviewers was 96.5% and 93.0% between TS and FFPE, and 91.1% and 92.5% between FS and FFPE, respectively. The combination of both intraoperative consultation techniques showed similar congruence but a slight improvement for the sensitivity (0.75 to 0.875) for the diagnosis of tumor at the resection margin in FFPE for Reviewer 1 but was unchanged for Reviewer 2. Conclusion. The additional evaluation of TS can be a helpful additional tool for intraoperative margin assessment of breast cancer specimens, in particular, when processing artifacts of FS are encountered.