A National Analysis of Positive Margins in Oropharyngeal Cancer Patients Undergoing Transoral Robotic Surgery

Introduction: Transoral robotic surgery (TORS) is associated with lower positive margin rates (PMR) and improved survival than conventional resection. However, the clinical variables associated with positive margins remain incompletely analyzed on a national level.

Methods: Retrospective analysis of patients over 18 years old with oropharyngeal cancer using the 2019 Patient User File of the National Cancer Database. Patients were stratified based on margin status and baseline patient characteristics were analyzed using univariate tests. Clinical variables were tested for associations with positive margins using univariable and multivariable logistic regression. Odds ratios (OR) and 95% confidence intervals (CI) were generated in the models.

Results: After exclusions, 4,294 patients were included. The PMR was 16.6%. High-volume facilities demonstrated lower PMR than low-volume facilities (11.4% vs 20.1%, p< 0.001) while academic facilities likewise displayed lower PMR than nonacademic centers (15.1% vs 23.9%, p< 0.001). PMR increased with with T stage (T1 = 13.0%, T2 = 18.0%, T3 = 26.7%, T4a = 38.3%, p< 0.001). For histological analysis, HPV-positive SCC had the lowest PMR (13.6%) compared to HPV-negative SCC (18.0%), HPV-unknown SCC (19.9%), and salivary gland carcinomas (24.6%, p< 0.001).

There were several clinical factors that were associated with positive margins on multivariable regression including non-high volume facility (OR1.7, 95%CI [1.4-2.1]), non-academic facility (OR1.4, 95%CI [1.2-1.8]), T stage (T1 ref, T2: OR 1.5 [95%CI 1.2-1.7], T3: OR 2.5 [95%CI 1.8-3.4], T4a: OR 4.1[95%CI 2.6-6.7]) and histologic type (ref HPV positive SCC, HPV-negative SCC (OR1.4, 95%CI [1.1-1.7]), HPV-unknown SCC (OR1.4, 95%CI [1.1-1.7], and salivary gland carcinomas (OR1.6, 95%CI [1.0-2.5]).

Conclusions: This study provides a comprehensive, national analysis of clinical factors that are associated with positive surgical margins including some variables not previously assessed including a broader range of histologic types of oropharyngeal cancer.