Factors Associated with Surgical Margin Revision Using Frozen Section Analysis in Oral Squamous Cell Carcinoma

Latham, Christopher

Statement of the Problem: The presence of a positive margin after ablative surgery has therapeutic and prognostic implications in patients with oral cavity carcinoma. The intraoperative clinical assessment of tumor margins is difficult and the use of frozen section (FS) analysis helps guide the adequacy of the resection and allows for immediate revision of the operative bed when necessary. The aims of this study were to determine whether the need for immediate, repeated resection in patients with a positive FS margin or the rate of diagnostic discrepancy between the FS analysis and the permanent section review was associated with tumor location, size, grade or node status.

Materials and Methods: According to an IRB-approved protocol, the pathology reports of patients with oral cavity squamous cell carcinoma who underwent surgical treatment at the Mayo Clinic from 2009-2011 were reviewed.

Data Analysis: Statistical analysis was performed using JMP 9.0 software. Descriptive statistics are reported as averages and ranges, and association between predictors and outcomes was determined utilizing t-test and chi-square. Statistical significance was defined as p <0.05.

Results: A total of 90 subjects met inclusion criteria, 41% (37) were female and 59% (53) were male, with a mean age of 64 years (25-93). Most common anatomic locations of the tumor were tongue (33%) and floor of mouth (25%). Distribution of tumor size was CIS in 5 (5.55%), pT1 in 40 (44.44%), pT2 in 24 (26.66%), pT3 in 9 (10%), pT4 in 11 (12.22%), and unknown in 1 (1.11%). Cervical node status was pN0 in 29 patients (32.22%), pN1 in 12 (13.33%), pN2a in 4 (4.44%), pN2b in 17 (18.88%), and pN2c in 3 (3.33%); lymph node dissection was not carried out in 25 patients. Six patients were identified with grade I histology (6.66%), 24 with grade II (26.66%), 48 with grade III (53.33%), 4 with grade IV (4.44%), and 8 unspecified (8.88%). Revision of a positive surgical margin was performed in 42 patients (46.66%). The accuracy of FS analysis after permanent section review was correct in 85 patients (94.44%). There was no correlation between the predictor variables and the accuracy of FS analysis. The need for margin revision was statistically significant with the histologic grade of the primary lesion (p=0.0007).

Conclusion: Frozen section analysis is a reliable technique in surgical head and neck oncology that provides details to help guide intraoperative treatment decisions. The study results indicate a correlation between the histologic grade of the primary tumor and the proclivity of surgical margin revision using frozen section analysis. Of the 42 patients that required revision of a surgical margin, 32 patients had grade III or IV histology. The overall diagnostic discordance between frozen sections and the permanent section reviews was low (5.6%), with only 2 patients having amendments of margin status that could have had treatment and outcome implications. The other 3 subjects with pathology report modifications were related to node status, which is not typically reported during frozen section analysis in most institutions and would have not altered the operative plan. The intraoperative analysis of frozen sections is a valuable adjunct in the treatment of oral squamous cell carcinoma, particularly in high-grade tumors.

References:

Patel R, Goldstein DP, Guillemaud J, et al. Impact of Positive Frozen Section Microscopic Tumor Cut-Through Revised to Negative on Oral Carcinoma Control and Survival Rates. Head & Neck 2010; 32:1444-1451.
Kwok P, Gleich O, Hubner G, Strutz J. Prognostic Importance of “Clear vs. Revised Margins” in Oral and Pharyngeal Cancer. Head & Neck 2010; 32:1479-1484.