Changes in Tumor Size and Margins due to Specimen Processing

Abstract

Objective: 1) Identify and quantify changes that occur in tumor size and tumor-free margins between surgical resection and gross pathologic analysis of oral cavity squamous cell carcinoma specimens. 2) Determine the extent to which these changes occur before or after tissue fixation in formalin.

Method: Preliminary analysis of this ongoing prospective study is presented. Patients with oral cavity squamous cell carcinoma undergoing surgical resection were included. Mucosal reference points were marked with sutures, representing tumor diameter and 2 separate resection margins. Measurements were recorded immediately before resection, after resection, and after fixation in formalin.

Results: Specimens from 16 patients were examined. From before resection to after formalin fixation, tumor size decreased by a mean of 3.05 mm (95% CI 0.54-5.56 mm), an 11.2% reduction, P = .02. Most of this decrease (mean, 1.94 mm, 95% CI 0.04-3.84 mm) occurred between the pre- and postresection measurements (before formalin fixation), P = .046. Margins decreased by a mean of 0.84 mm (95% CI 0.12-1.57 mm) from preresection to postfixation, an 11.2% reduction, P = .025. All of this decrease occurred prior to formalin fixation.

Conclusion: Preliminary analysis suggests that mucosal dimensions of both tumor and tumor-free margins in oral cavity squamous cell carcinoma specimens decrease between surgical resection and gross pathologic analysis. Most of this decrease occurs prior to fixation, especially for margins, and may be due to intrinsic tissue properties rather than formalin effects.