New opportunities for preoperative diagnosis of anaplastic thyroid cancer

Background. Anaplastic thyroid cancer (ATC) is one of the most aggressive human tumors. Since median survival of ATC patients is only 4 months, its early diagnosis is very important. Although ATC has specific clinical manifestations, the analysis of expression of different microRNAs can facilitate preoperative diagnostics and help to detect its potential precursors among differentiated cancers and other thyroid malignancies. The study objective is to identify microRNAs specific for ATC that are different from microRNAs in other thyroid cancers. Materials and methods. We analyzed the expression of 14 microRNAs in histological specimens of 67 patients with ATC. The control groups included 25 patients with benign nodules, 36 patients with follicular adenomas, 32 patients with follicular cancer, and 152 patients with papillary thyroid cancer. For 7 out of 67 ATC patients, we compared mi-croRNA levels in histological and cytological specimens. Results . Patients with ATC demonstrated a statistically significant decrease in the expression of miR-145, miR-125b and increase in the expression of miR-155 and miR-21 compared to all control groups. We found two reliable diagnostic markers of ATC: relative miR-21 expression (at a cutoff of 14.9, sensitivity was 0.955 and specificity was 0.837) and the miR-21/miR-145 ratio (at a cutoff of 122, sensitivity was 0.955 and specificity was 0.955). The level of miR-21 expression and miR-21/miR-145 ratio in cytological specimens were accurate in all 7 cases (100 %). Conclusion. the level of expression of specific microRNAs can be used as a reliable biomarker for ATC. The consistency between the results obtained in cytological and histological specimens enables the use of stained cytological samples for this analysis.