Intraoperative Pathology Consultation in Patients With p16-Positive Unknown Primary Squamous Cell Carcinoma.

ABSTRACT

Importance Current guidelines recommend intraoperative frozen section(s) during diagnostic surgery for squamous cell carcinoma for unknown primary tumors (SCCUP). Objective: To determine the utility of intraoperative pathology consultation during transoral robotic surgery (TORS) in localizing primary tumors and influencing need for adjuvant therapy. Design, Setting, and Participants: A retrospective case series including 47 adult patients with human papillomavirus (HPV)-associated SCCUP who underwent TORS/oropharyngectomy between January 2016 and February 2023 was carried out at a single tertiary care hospital. The analysis took place on May 13, 2024. Exposures Nodal stage, tonsillectomy history, extranodal extension (ENE). Main Outcomes and Measures: Intraoperative pathology consultation and final pathology results were compared with surgical outcomes, including margin revision, need for second procedure and/or radiation with or without chemotherapy. Results: This study included 47 adult patients. Mean (range) age was 61 (41-79) years; patients were mostly men (37 [79%]). Overall, primary tumors were identified in 37 patients (79%), including all cases with positive nodes involving more than 1 neck level. Patients whose primary tumor was not found tended to have tobacco use history (8/10 vs 13/37 [35%]; difference, 45%; 95% CI, 16%-74%) and absence of ENE (8/10 vs 15/37 [41%]; difference, 39%; 95% CI, 10%-68%). Primary tumor was identified intraoperatively in 18 of 37 patients (49%). SCCs identified intraoperatively were significantly larger than SCCs found on permanent sections only mean (SE), 1.2 (0.13) cm vs 0.5 (0.1) cm (difference, 0.7 cm; 95% CI, 0.53-1.94). The sensitivity, specificity, positive predictive value, and negative predictive value of intraoperative consultation was 49% (95% CI, 33%-64%), 100% (95% CI, 100%-100%), 100%, and 34% (95% CI, 19%-53%), respectively. Margins were revised in 11 of 18 patients (61%) whose primary tumor was identified intraoperatively (during original procedure) and in 3 of 19 patients (16%) whose primary tumor was identified on permanent pathologic findings only (during a second procedure) (11/18 [61%] vs 3/19 [16%]; difference, 45%; 95% CI, 17%-73%). However, there was no significant difference in the use of adjuvant radiotherapy with or without chemotherapy or need for a second procedure based on intraoperative primary tumor localization. Conclusion and Relevance In this case series study, the sensitivity and negative predictive value of intraoperative pathology consultation among 47 patients was less than 50%. Given the lack of influence on the need for radiotherapy with or without chemotherapy or second procedure, the practical utility of routine intraoperative frozen section requires further scrutiny.