HER-2÷neu expression in different histological subtypes of papillary thyroid carcinoma.

The identification and validation of new, complementary prognostic factors represents a challenging issue in thyroid pathology, opening the perspective of papillary thyroid carcinoma (PTC) stratification based on differences of aggressiveness at molecular level. Our study aims to analyze the HER-2÷neu expression in different subtypes of PTC and its relationship with the classical clinicopathological factors. We investigated 120 cases of sporadic PTC. The cases were selected based on the histological criteria reported to clinical course and prognosis and distributed in two different subgroups, namely low- and high-risk. HER-2÷neu expression was assessed using an adapted semiquantitative score proposed for thyroid carcinomas. The correlations between HER-2÷neu expression and clinicopathological prognostic factors were statistically analyzed. HER-2÷neu positivity was found in 25 (20.8%) cases, from which 20 cases were classified as subtypes with low-risk and five with high-risk; 95 (79.2%) cases were HER-2÷neu negative, 53 cases being included in low- and 42 cases, respectively, in high-risk group. HER-2÷neu expression was significantly associated with histological subtypes, extrathyroidal extension, and tumor focality. Our results highlight the potential of HER-2÷neu as supplementary marker useful for the stratification of PTC in low-risk and high-risk histological groups, along with the well-known clinicopathological prognostic factors. Our data could be considered as new evidences that indicate different involvement of HER-2÷neu in tumor development and behavior, possible due to its connection with other factors present in the molecular environment.