Background:
Gene expression profiling (GEP) is a powerful mean of dissecting the biology of cancer. Here, it has been used for the first time to characterize and compare norma thyroid tissues removed during surgery.

Material and Methods:
A triple-blind prospective study was performed between May and October 2013 on 45 consecutive patients (13 M, 32 F; mean age: 52.8 years) who underwent thyroid surgery. A normal sample of the gland was isolated during operation and a comparative gene expression profiling was performed. Total RNA was isolated and the whole-GEP was determined. Raw data were extracted and computed normalized. Unsupervised analysis performed by Pearson correlation was applied to a subset of 50 genes which average change in fold expression levels (ACFEL) varied mainly from the mean across the whole panel. GEP was validated by qRT-PCR (significance by the Wilcoxon signed-rank test).

Result:
Unsupervised analysis showed high samples clustering according to similar pathology: carcinoma, goitres, hyperfunctioning disease, normal tissues from patients with parathyroid disease. 50 genes were found differentially expressed at relatively high stringency (1.7 ACFEL). Seventeen genes showed a p-value < 0.05 and their differences were significant. Functional annotation revealed a role of these genes in the immune system response, and cell activation. The differential expression of all 17 genes was confirmed by qRT-PCR (p<0.05).

Conclusion:
The distinct GEP detected may influence the insurgence and/or progression of thyroid cancer, its molecular classification, and thus pinpoint selective gene targets for new preoperative diagnostic approaches treatments and prophylactic strategies.