SAT-LB096 Relationship between MicroRNA Expression Levels and Clinicopathological Parameters and Recurrence of Papillary Thyroid Carcinoma

Introduction: Papillary thyroid carcinoma (PTC) is the most common type of endocrine cancer. Although PTC is a malignancy that has a good prognosis, disease progression occurs in up to 20 % of patients. Currently, recurrence risk stratification is accomplished by using clinicopathologic factors, despite their limited prognostic value. Number of biomarkers for PTC recurrence prediction is still very limited. Identification of possible associations of traditional clinicopathological parameters of disease recurrence with molecular biomarkers of PTC may help better understanding the carcinogenesis and improving the clinical management of patients with PTC. Objectives: The aim of this study was to identify specific miRNAs as biomarkers for predicting the recurrence of PTC and to analyze the association between miRNAs expression levels and clinicopathologic characteristics of PTC. Methods: We selected 5 miRNAs (miRNA- 146b, -222, -21, -221 and -181b) and measured the expression levels of these miRNAs in 400 FFPE PTC tissue specimens and compared the levels of selected miRNAs expression to healthy thyroid tissue. We also analyzed the correlation between miRNAs (- 146b, -222, -21, -221 and -181b) expression and clinicopathologic characteristics of PTC. Results: Levels of miR-146b, miR-222, miR-21, miR-221 and miR-181b expression in PTC tissue samples (n = 400) were compared with those in healthy thyroid tissue (n = 4). All miRNAs were over-expressed in PTC tissue compared to healthy thyroid tissue (p ˂ 0.01, p ˂ 0.01, p ˂ 0.01, p ˂ 0.01 and p = 0.19 respectively). Higher expression levels of miRNAs (miRNA-146b p<0.01; miRNA-222 p<0.01; miRNA-21 p<0.01; miRNA-221 p=0.01; miRNA-181b p<0.01) were observed in recurrence PTC patients (n = 87) compared to non-recurrence PTC patients (n = 313). Expression levels of all miRNAs were significantly higher in lymph node metastases-positive group (n=91) compared to lymph node metastases-negative group (n=309) (p < 0.01). Younger patients had similar expression levels of miR-146b, miR-222, miR-21 and miR-221 as compared to older patients (p=0.11, p=0.944, p=0.485, p=0.314, respectively). Only miR-181b was over-expressed in patients younger than 45 years compared to older patients (p=0.007). Conclusion. The levels of miRNA-146b, - 222, -21, -221 and -181b expression in PTC were strongly associated with PTC recurrence and lymph node metastases. Selected miRNAs did not show age-related differences in expression, suggesting that mechanisms other than age may influence the expression of these miRNAs. However, the prognostic value of these miRNAs is rather limited in individual cases as the distribution of miRNA expression overlaps between patients with high and low risk of PTC recurrence. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.