Endocrine Abstracts

It is still debated if the coexistence of papillary thyroid cancer (PTC) with a thyroid autoimmune process is associated with a better or worst outcome. Moreover, though a direct relationship between oncogenes and the activation of a pro-inflammatory program has been documented, the genetic background of PTCs with associated autoimmunity is not known.

Aim of the present study was to to investigate the clinical and molecular features of PTCs associated or not with autoimmunity. A large series of PTCs associated or not with thyroiditis and followed up according to recent guidelines has been clinically evaluated. Moreover, the genetic background of these two Groups of tumors was studied by means of RET and BRaf molecular analyses. In some cases, the thyroid tissue of the lobe controlateral to the tumor was also analyzed. No significant differences were found between the two Groups regarding either the clinical and pathological features, or the outcome. Interestingly, the molecular defects were significantly different among patients with PTC associated or not with thyroiditis (P=0.001), being ret/PTC1 significantly more represented in patients with PTC and autoimmunity, and BRaf in patients with PTC alone. A ret/PTC rearrangement was also found in 41% of non-neoplastic thyroiditis tissues controlateral to tumors harbouring either ret/PTC or BRaf or none mutations.

In conclusion, the whole of present findings extend the knowledge about the tight relationships between oncogenes, thyroiditis and thyroid cancer. A significantly different genetic background between PTCs with or without associated autoimmunity was firstly demonstrated, well in agreement with the recent finding that, in normal human primary thyrocytes, ret/PTC1 activates a transcriptional program related to inflammation. Moreover, the presence of ret/PTC in inflammatory tissues associated with non-ret/PTC tumors, indicate that inflammation could predispose to carcinogenesis even if this is driven by different genetic alterations.