Circulating microRNA as potential diagnostic and prognostic biomarkers of well-differentiated thyroid cancer: A review article.

Half of all people aged 50 and over develop a thyroid nodule in their lifetime, exclusion of cancer is required in each case. Nodule tissue sampling is performed by way of fine needle aspiration biopsy (FNAB), however a definite diagnosis is possible only in 30% of cases. The discovery of a diagnostic biomarker to discriminate between thyroid cancer and benign nodules would therefore greatly improve current clinical practice. Using the databases of Medline, Embase and Pubmed we identified 21 original research papers examining various microRNA as potential biomarkers. Currently, the most evidence supporting diagnostic utility exists for miRNA-222. It has been shown repeatedly to have potential in diagnosis of PTC & MTC as well as being linked with the most prognostic factors of all microRNA. To a lesser extent, evidence seems to support the diagnostic and prognostic utility of miR-146b, Let-7 family, miR-221 for PTC and miR-21 for PTC & FTC. MicroRNA appear to show promise as potential diagnostic and prognostic biomarkers, however there is still not enough data to produce a consensus. Continued research should be undertaken with streamlined protocols.