Abstract 2574: The effect of epidermal growth factor expression in detecting oropharyngeal tumors during fluorescence-guided robotic surgery
Authors: Stone Logan , Rao Shilpa M. , Gonzalez Manuel Lora , Lin Diana , Jeyarajan Hari , Thomas Carissa M. , Warram Jason 
Published: March 2024

Intro: Oropharyngeal squamous cell carcinoma (OPSCC) has been shown to overexpress epidermal growth factor receptor (EGFR), making it a targetable biomarker for fluorescently labeled monoclonal antibodies such as panitumumab-IRDye800, which can be used during fluorescence-guided trans oral robotic surgery (TORS). Although antibody-based fluorescence-guided surgery is being evaluated in several late-stage trials, the use of intraoperative fluorescence imaging for TORS has not been thoroughly explored. We observed that the bi-polar cautery tool[AHM(1] of the TORS robot was auto-florescent and would appear dimmer in the presence of fluorescence from surgically exposed tumor. We aim to characterize the florescence contrast of the tool and tumor to create a rapid qualitative assessment on tumor presence.

Methods: During a phase 2 clinical trial evaluating panitmumab-IRDye800 fluorescence-guided TORS of OPSCC, consenting patients (n=12) with biopsy-confirmed OPSCC received 50mg panitumumab-IRDye800 48 hours prior to surgery. Intraoperative fluorescence images were acquired using the onboard fluorescence camera of the Da Vinci Xi robot and post-operation fluorescence exams were conducted by the Pearl and Odyssey Systems (Li-Cor)[BK2]. For each patient, 3 intraoperative views (pre, mid and late resection) showing pathology-confirmed tumor, normal mucosa, and the tool were taken, and several frames from each view were analyzed via ImageJ to calculate mean fluorescence intensity (MFI) in regions of interest. The MFI of tumor and normal muscoa was normalized with MFI of the tool to obtain a standard fluorescence ratio (SFR) per patient[BK3]. A paired t-test was used to compare differences in MFI between the tumor and tool or normal mucosa.

Results: The MFI for each time point was graphed for the tool, tumor and normal mucosa. Significant differences were found between tumor and mucosa and tumor and tool for every time point. Tumor/tool SFRs per patient ranged from 2.1 to 60.9, while normal/tool SFRs ranged from 0.4 to 3.1. Receiver operator characteristics curve analyses of tissue-to-tool SFR data showed a sensitivity of 90.9% and a specificity of 96% to identify the presence of tumor.

Conclusion: The auto-fluorescent properties of the bipolar cautery tool of the Da Vinci Xi robot can be used for qualitative assessments of tumor presence during fluorescence-guided TORS. Bright fluorescence from the tool relative to surrounding tissue suggests the lack of carcinoma presence, which could confirm the surgeon’s complete resection of OPSCC.

Citation Format: Logan Stone, Shilpa M. Rao, Manuel Lora Gonzalez, Diana Lin, Hari Jeyarajan, Carissa M. Thomas, Jason Warram. The effect of epidermal growth factor expression in detecting oropharyngeal tumors during fluorescence-guided robotic surgery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2574.