Preanalytical Phase Tumor Contaminants in Intraoperative Margins From Transoral Robotic Surgeries

Tumor contaminants were incidentally noted in frozen section margins of oropharyngeal squamous cell carcinoma.

To estimate the frequency of tumor contaminants in frozen section slides of patients who underwent surgery for pharyngeal cancer, and to characterize the surgical and pathologic context of these incidents.

A retrospective search was conducted to identify pharyngeal resections from 2016 to 2022. Surgical pathology, operative reports, and frozen section slides were reviewed. Preanalytical phase tumor contaminants were defined as tumor contaminants that occurred in frozen section slides with or without occurrence in permanent slides.

Eighty-one pharyngeal resections with intraoperative tumor bed margins for squamous cell carcinoma were identified. These included 308 tumor bed margins represented in 641 slides. Preanalytical contaminants occurred among 9 patients (11.1% of all and 21.4% of robotic surgeries) and in 3.8% of the 308 intraoperative tumor bed margins. A statistically significant association was found between contaminants and larger tumor size (Student t test, P = .04) and surgical approach (robotic versus open oropharyngectomy: Fisher exact test, P < .001). All patients with contaminants had intraoperative tumor disruption. Two frozen section deferrals (0.6%) and 2 discrepancies with final diagnosis (0.6%) attributed to contaminants were identified; however, clinical or surgical management was not affected in any patient.

Preanalytical contaminants may cause confusion in intraoperative margin assessment. They are more likely to occur in margins of nonkeratinizing squamous cell carcinoma resected by transoral robotic surgery if there is intraoperative tumor disruption. Rarely, preanalytical contaminants lead to frozen section deferral or discrepancy with final diagnosis.