RESUMO
Several prognostic factors affect the outcome of thyroid carcinomas including tumor stage and distant metastases. Nm23 is a metastasis suppressor gene and has a crucial role in the control of metastatic potential of several carcinomas. The aim of our study is to evaluate expression of nm23 marker in benign and malignant thyroid neoplasms using the immunohistochemistry method and to elucidate its relationship with tumor size, vascular or capsular invasion and lymph node involvement. In a descriptive study, 200 paraffin blocks comprising of 38 benign and 162 malignant thyroid neoplasms stained with nm23 marker were studied. Cytoplasmic staining in more than 10% of cells was considered as positive. The relationship between nm23 and tumor size, vascular or capsular invasion, lymph node involvement was analysed using SPSS 11.5 software [p=0.05]. There was 40% positive incidence of nm23 in follicular adenoma, 87.5% in hurthle cell adenoma, 67.2% in papillary carcinoma, 66.7% in follicular carcinoma, and 64.7% in medullary carcinoma. In follicular adenoma, frequency of nm23 positive tumors was directly correlated to tumor size [p=0.04]. There are no statistically significant correlation between nm23 and tumor size, vascular or capsular invasion or lymph node involvement in malignant thyroid neoplasms. In papillary and medullary carcinoma, negative predictive value of nm23 for lymphnode involvement was over 80%. Also in follicular carcinoma, sensitivity and negative predictive value of nm23 for vascular invasion were approximately 90%. Lack of significant correlation between nm23 and tumor invasiveness [and probably metastasis] factors, demonstrate that although nm23 is a potentially metastasis suppressor gene, whereas in many other tumors it may play a different role in thyroid neoplasms, a role which necessitates further studies to be conducted