(630) Impact of tumor floater contaminants in margin analysis for transoral robotic surgery (TORS)

Introduction: Floaters represent detached fragments of tumor during surgery that confound histologic analyses, specifically in intraoperative margin assessment. We examine the incidence and management of floaters in the context of transoral robotic surgery (TORS) for oropharyngeal carcinoma (OPC).

Methods: Multi-institutional retrospective analysis of TORS cases from September 2014 to October 2025. Occult primary OPC cases where no primary site was identified were excluded. Floater contaminants were reviewed and confirmed by a dedicated head and neck pathologist. Floater status was compared with respect to institution, surgeon, and treatment rendered.

Results: Of 220 TORS cases, 185 cases were deemed eligible for analysis. Mean age was 63.4 years (SD ± 9.3) across a spectrum of T-stage (T1: 50.8%, T2: 41.1%, T3: 7.6%, T4: 0.5%) and sex (male: 85.4%, female: 14.6%). Overall, 10.3% (19/185) demonstrated histopathologic floaters on margin analysis. Floater incidence stratified by institution was similar: (Site A: 9.3% (5/54), Site B: 10.7% (14/131), p=0.83). Floater incidence stratified by surgeon showed no significant difference (Surgeon A: 9.3% (5/54), Surgeon B: 11.1% (3/27), Surgeon C: 9.8% (8/82), Surgeon D: 13.6% (3/22), p=0.95). Report descriptors included terms such as “detached”, “disrupted”, “focus”, or “fragment.” Floaters were identified on frozen section in 52.6% (10/19) of cases and permanent in 47.4% (9/19) of cases. Although floaters may represent a false-positive oncologic margin, their ambiguity led to additional resection (68.4% (13/19)), wider radiation fields (21.1% (4/19)), or intensified adjuvant therapy (5.3% (1/19)).

Conclusions: Across institutions and surgeons, the presence of tumor floaters in TORS was found to be consistently and unexpectedly high. False-positive interpretation of floaters on margin analysis may result in unnecessary re-resection, trimodality therapy, and increased morbidity. The friable nature of OPC within a constricted transoral space may contribute to cross-contaminant diagnostic error.