8414 Utilization of Cell Free DNA Integrity Index to Differentiate Benign from Malignant Thyroid Nodules

Abstract Disclosure: S. Tarafdar: None. S. Dutta: None. P. Mukhopadhyay: None. N.P. Bhattacharya: None. S. Ghosh: None. Introduction: Recent advances in molecular genetics have evaluated a potential role for plasma cell-free DNA (cfDNA) integrity index as a non-invasive cancer marker. Data on cfDNA integrity in differentiated thyroid cancer is sparse and needs to be investigated further. Aim of the study: The purpose of this study is to investigate the hypothesis that longer DNA strands in plasma may serve as a marker for thyroid cancer. Methods: Patients presenting with thyroid nodules underwent ultrasonography with Thyroid Image Reporting and Data Systems (TIRADS) scoring and FNAC (Bethesda classification).Patients with Bethesda 3, 4, 5, and 6 had surgery and confirmation by histopathology. Patients with Bethesda 2 presenting with compressive symptoms and cosmetic concerns underwent surgery; the remaining patients were considered benign based on clinical follow-up, USG, and FNAC characteristics. Blood sample collected prior to FNAC was used to extract and quantify cfDNA. To assess the integrity index 180/67, 306/67, and 476/67 for the APP gene, we used a quantitative real-time PCR (qPCR) method based on the quantification of four amplicons of varying lengths (67, 180, 306, and 476 bp, respectively). Because culture cells had extremely intact genomic DNA, the genomic DNA obtained from the MDA-T32 papillary thyroid cancer cell line was utilised as a reference to estimate the relative DNA strand integrity in plasma DNA. To determine the (ΔCt) value for 67,180, 306, and 476 bp, the Ct value of the sample was subtracted from that of the MDA-T32 control. Results: A total of 161 subjects were recruited, of these 92 were benign and 69 had differentiated thyroid cancer(confirmed by histopathology). Using the 180/67 bp integrity index benign thyroid nodule patients had significant lower value (median 0.39, 95% CI: 0.33-0.46) compared to patients with differentiated thyroid cancer (median 0.62, 95% CI: 0.56-0.68). A cfDNA integrity index of 180/67 bp could significantly differentiate between benign and malignant thyroid nodules (P0.001). However, there was no significant difference between malignant and benign thyroid nodules based on the cell free DNA integrity indexes of 306/67 and 476/67. Conclusions: The cfDNA integrity score of 180/67 exhibits potential as a circulating marker for the detection of thyroid nodules and as a means of monitoring cfDNA fragmentation in patients with thyroid cancer. However, further confirmation through prospective trials is necessary. Presentation: 6/3/2024