Comparison of intraoperative ex-vivo electrical impedance measurements for oral squamous cell carcinoma.

Abstract

e18100 Background: Oral squamous cell carcinoma (OSCC) is a prevalent, lethal cancer representing 4.6% of global cancer-related deaths. 60% of oral cancers are diagnosed at advanced stages with a 5-year survival rate of only 40%. Primary treatment for oral cancers often involves surgical resection. However, this approach can be limited by the presence of positive resection margins, which occur in nearly 13% of cases. Previous research has demonstrated the utility of electrical impedance spectroscopy (EIS) in detecting variations in the electrical properties of tissue and has applications in the setting of oral cancers. This study used an impedance sensing probe to evaluate differences in electrical impedance between healthy, dysplastic, and malignant oral tissue intraoperatively on ex-vivo sample tissue. Methods: 86 total patients undergoing OSCC resection (n=67) and biopsy (n=19) at Dartmouth-Hitchcock Medical Center were enrolled under an IRB-approved protocol. Many patients had multiple abnormal tissue sites resulting in 187 total samples. Electrical impedance was measured using a custom-designed 11mm diameter electrode array with a 3D-printed probe, capturing data from ex-vivo lesions and healthy tissue. Sample resistance, reactance, phase, and impedance magnitude were recorded at 31 logarithmically spaced frequencies between 0.1-100kHz and analyzed using MATLAB. Unpaired t-tests compared impedance parameters between tissue groups: healthy, cancer, dysplasia (low, moderate, high). Results were validated against pathologic assessments at each probe site. Reporting of interim data results approved by the study’s Data and Safety Monitoring Committee. Results: Reactance and resistance are significantly lower in malignant tissue compared to healthy tissue (p<0.0001) for most frequencies. AUCs for resistance and reactance were 0.85 at 500Hz and 0.87 at 6.3kHz, respectively. Resistance is significantly lower (p<0.005) in malignant tissue compared to healthy tissue for all frequencies except 12.6kHz. Resistance significantly differentiated between and healthy tissue for only two frequencies (p<0.005). Reactance is significantly lower (p<0.05) in malignant tissue compared to healthy tissue and dysplastic tissue for all frequencies except for 100kHz. Conclusions: This study demonstrates the feasibility and efficacy of EIS in differentiating oral cavity tissues based on their electrical characteristics. Analysis of resistance and reactance measurements yielded an AUC>0.85, indicating a strong ability to discriminate between healthy, dysplastic, and malignant tissues. These findings suggest that EIS may have potential as a non-invasive and objective diagnostic tool for intraoperative use. This data can be used for development of EIS technology for eventual outpatient utilization. Clinical trial information: NCT05430477 .