Lack of HER-2 gene amplification and association with pathological and clinical characteristics of differentiated thyroid cancer.

Human epidermal growth factor receptor 2 (HER-2) is a well recognized prognostic and predictive factor in breast cancer. However, the role of HER-2 in thyroid cancer remains controversial. The aim of this study was to evaluate HER-2 expression in differentiated thyroid cancer (DTC) and determine whether there is an association with other clinical and pathological characteristics. A total of 69 patients with DTC were investigated, 58 of whom had papillary and 11 follicular carcinomas. HER-2 was detected by immunohistochemical examination on sections from formalin-fixed, paraffin-embedded tumor tissues. Tumors with HER-2 expression classed as +1 and +2 were retested with chromogenic in situ hybridization. Clinicopathological data were retrieved from the hospital records of the patients. HER-2 overexpression was found in 4 (6.9%) of the 58 patients with papillary carcinoma, whereas there was no HER-2 overexpression in any of the 11 cases of follicular carcinoma. There was no association of HER-2 expression with tumor size, pathological grade and cervical lymph node metastasis. In conclusion, there were no HER-2 positive cases of follicular carcinoma and the incidence of HER-2 overexpression in papillary carcinoma was very low. Thus, HER-2 cannot be used routinely as a prognostic or predictive factor in DTC. The expression of other epidermal growth factor receptors in DTC merits further investigation.