Discriminating thyroid cancers from benign lesions based on differential expression of a limited set of miRNA using paraffin embedded tissues.

ABSTRACT

Background: Micro-RNAs (miRNAs) are expressed in a tissue-specific manner and are known to demonstrate differential expression even among the various subtypes of a given tumor. This differential expression has been harnessed successfully in the development of diagnostic assays for various malignant tumors. These assays have been found to be relevant and of value as additional diagnostic tools even among thyroid tumors, particularly with regard to thyroid carcinomas of follicular morphology. Materials and Methods: A limited set of miRNA have been assessed as part of this study in an effort to use minimal number of miRNA markers (miR-187, miR-221, miR-222, and miR-224) to differentiate the benign from the malignant thyroid tumors using miRNA derived from paraffin embedded material. Results: While miR-221 and miR-222 were found to provide good accuracy as individual markers (86% and 84%), a combination of the two provided slightly better accuracy (91%). Both miR-221 and 222 were able to significantly differentiate malignant tumors from the benign samples (P< 0.001) individually and as a combination of markers. However, inclusion of miR-187 and miR-224 in the panel did not provide any additional benefit. Conclusion: While a combination of miR-221 and 222 when used in a diagnostic panel could provide fairly good accuracy additional markers may need to be investigated to augment their diagnostic utility.