Abstract 18: Circulating cell free long-noncoding RNA (PVT1 and MALAT1) expression in determining malignancy in indeterminate category of thyroid nodules

Background: Molecular genetics is useful in indeterminate thyroid nodules. Long non-coding RNA (lncRNA) has possible role in tumorogenesis of various cancers. Objective: We determined expression of lncRNA from plasma in individuals with indeterminate thyroid nodules. Methods: Patients underwent ultrasonography (USG) and guided FNAC, surgery (where indicated). Total RNA was extracted from plasma using standard kits and expression of specific lncRNA was determined by quantitative RT-PCR. Initially a cutoff was determined by comparing ÄCt of benign, malignant with healthy controls and it this was validated in indeterminate category. Results: FNA (n =182) suggested benign (n= 97) and malignant (n=31) and they underwent histopathological confirmation. PVT1 & MALAT1 lncRNA were significantly up regulated in malignant cases compared to healthy and benign group. A PVT1 (ÄCt) cut-off of 2.29, AUC of 0.995 (95% CI, 0.98-1.0) and a MALAT1 (ÄCt) cut-off of 3.33, AUC of 0.997 (95% CI, 0.99-1.0) was established to predict malignant nodules. Using this cut-off in indeterminate nodules (n=54w) were able to determine malignancy (sensitivity and specificity for PVT1 was 93.5%, 95.6% and for MALAT1 was 77.4% and 100% respectively. Conclusion: PVT1 & MALAT1 expression from plasma could help in differentiating malignant from benign thyroid nodules in indeterminate thyroid nodules.