microRNA profile of human medullary thyroid cancer

To identify a microRNA profile of human medullary thyroid cancer (MTC), we performed a miRNA microarray analysis exploiting 8 primary tumours and 9 paired neck nodes metastases in comparison with 3 non-neoplastic thyroid tissues. Eight sporadic MTC patients were selected for the miRNA microarray analysis. A total of 17 MTC (P = primary tumour, M = nodal metastasis) and 3 non-neoplastic thyroid (N) formalin-fixed paraffin-embedded (FFPE) surgical specimens were obtained. The primary tumours and the matched nodal metastases were obtained from the initial surgery or from a subsequent lymphadenectomy. Referring to the matched primary tumour, 6 of the nodal metastases were synchronous and 3 were metachronous (one patient had both metastasis types included in the array). Non-neoplastic thyroid samples were obtained from patients with pathologies other than thyroid cancer. For each specimen haematoxylin and eosin-stained sections and calcitonin-stained sections were evaluated by an experienced pathologist to confirm the histological diagnosis and to select areas in which tumour cells represented at least the 80% of the total cells.