Shrinkage in oral squamous cell carcinoma: An analysis of tumor and margin measurements in vivo, post-resection, and post-formalin fixation.

ABSTRACT

PURPOSE: To quantify changes in tumor size and tumor-free margins following surgical resection and formalin fixation of oral cavity squamous cell carcinoma. MATERIALS AND METHODS: Nineteen patients were studied via cohort design. Between May and December 2011, measurements of tumor size and tumor-free margin were made in patients with squamous cell carcinoma of the oral cavity. Mucosal reference points were marked with sutures, representing tumor diameter and two separate resection margins. Measurements were recorded immediately before resection, after resection, and following fixation in formalin. RESULTS: The overall mean shrinkage in tumor size was 10.7% (95% CI 3.4-18.0, p=0.006). When comparing mean tumor measurements, most of the tumor size decrease (6.4%, 95% CI 0.4-12.4, p=0.039) occurred between pre- and post-excision measurements. To a lesser extent, tumor size decreased following formalin fixation. Comparison of tumor-free margin measurements revealed a pre-excision to post-fixation mean decrease of 11.3% (95% CI 2.9-19.6%, p=0.011), with a statistically significant decrease of 14.9% (95% CI 8.5-21.3%, p<0.001) occurring between pre- and post-excision, and no significant decrease from post-excision to post-formalin fixation. CONCLUSION: Mucosal dimensions of both tumor and tumor-free margins in oral cavity squamous cell carcinoma specimens decrease between surgical resection and 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.