Endocrine Abstracts

Background: Papillary thyroid carcinoma (PTC) is the most frequently occurring endocrine malignancy, with an increasing rate of incidence over the last three decades. Generally, PTC has an excellent prognosis with a relatively low mortality rate, but a small portion of PTC patients suffers from an aggressive form of the disease with tumor invasion and metastasis. Analysis of miRNAs expression data may improve perioperative decision making for patients with PTC.

Aim of the study: To settle the diagnostic utility of specific miRNAs in the preoperative assessment of thyroid nodules.

Methods: One hundred thyroid fine needle aspiration (FNA) samples with suspected thyroid carcinoma were collected in the prospective molecular study at Vilnius University hospital Santaros klinikos. The expression level of the selected five miRNAs (miR125a, miR146b, miR200b, miR221, miR4324) was verified by real-time PCR in 36 non-malignant nodule aspirate samples, 34 PTC without lymph node metastases (LNM) samples and 30 PTC with LNM samples.

Results: The relative expression levels of four miRNAs differed significantly between benign and PTC groups (P< 0.05). The relative expression levels of two miRNAs differed significantly between PTC without LNM and PTC with LNM groups (P< 0.05). A 16.002-fold increase in the value of miR146 increases the probability (odds ratio) that the disease will be cancerous without metastasis rather than benign (95% CI [4.188; 61.148]). A 4.187-fold increase in the value of miR146 increases the odds (odds ratio) that the disease will be cancerous with metastasis rather than benign (95% CI [1.692; 10.366]). A 31.917-fold increase in miR4324 value increases the odds (odds ratio) that the disease will be cancerous with metastases rather than benign (95% CI [5.966; 170.765]). A one-fold increase in miR4324 value increases the odds (odds ratio) that the disease will be cancerous with metastasis by 8.301 times more than non-metastatic (95% CI [2.155; 31.977]).

Conclusions: Our study showed that the expression analysis of four miRNAs (miR125A, miR221, miR146B and miR4324) could improve the accuracy of fine-needle thyroid node biopsy, which would allow a better differentiation of malignant from benign thyroid nodules. Analysis of miRNA expression levels and detection of miRNAs in FNAB can be used for the pre-operative diagnosis of thyroid cancer. To translate these data into clinical application, large cohort studies are required to examine the prognostic and diagnostic value of miRNAs.