Purpose of the study. To develop a diagnostic calculator for assessing the expression of profile microRNAs (miRNAs) that are significant for the oncogenesis of thyroid cancer, to introduce it into clinical practice and to evaluate the effectiveness of the proposed method for early diagnosis of malignant neoplasms of the thyroid gland in uncertain diagnostic situations after fine-needle aspiration biopsy (FNAB).Material and methods. The previously developed «Method for Diagnosing Malignant Neoplasms of the Thyroid Gland» (patent RU2820815 C1) was tested on 284 patients of the dispensary group with nodular formations of the thyroid gland according to the results of ultrasound and an uncertain conclusion after FNAB. The number of patients with papillary thyroid carcinoma was 83 (29,2%), follicular carcinoma 43 (15,1%) and with benign thyroid pathology (follicular adenoma) – 158 (55,6%) people. The expression of miRNA-146b and –574–3p in cytological samples of thyroid nodules after FNAB was assessed using the real-time PCR method.Results. In thyroid cancer patients, the expression of miRNA-146b was higher (p=0,007) compared to patients with benign pathology, while the expression activity of miRNA-574–3p was lower (p=0,013). To assess the index of reciprocal paired dysregulation of miRNA-146b and miRNA-574–3p expression in thyroid cells, it is recommended to determine the ratio of the expression values of the corresponding molecules. If the ratio index of miRNA-146b and miRNA-574–3p expression is higher than 4.5, then a conclusion is made about a malignant neoplasm of the thyroid gland. The diagnostic coefficient calculated by the developed formula using the logistic regression method also allows diagnosing malignant neoplasm of the thyroid gland when compared with the cutoff level. The proposed methods are highly informative.Conclusion. Evaluation of the expression of miRNA-146b and miRNA-574–3p in the cells of thyroid nodules obtained by FNAB allows improving the diagnosis of malignant pathology in mutation-negative thyroid nodules with uncertain FNAB results.
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