Value of the Expression of p21RAS, P53, Bcl-2 Oncoproteins and Ki-67(MIB-1) Antigen of Cellular Proliferation in the Diagnosis and Prognosis of Thyroid Tumours

Abstract

Introduction. The thyroid gland is a good organ for the study of genetic alterations in tumoural development and progress. The study of oncogenes and antigens of cellular proliferation is of interest. Materials and methods. 36 cases of thyroid adenomas, 58 papillary carcinomas, 32 follicular carcinomas, 2 anaplastic carcinomas and 12 medullary carcinomas were selected. Clinical and histological prognostic factors were studied and an inmunohistochemical study with Ki-67 (MIB-1), p53, Bcl-2 and p21 RAS antibodies was performed. Results.The proliferative rate Ki-67 (MIB-1) showed statistical differences in adenomas and follicular carcinomas. The p53 protein did not appear in adenomas, but was shown in those carcinomas with bigger histological dedifferentiation. A relationship was also established with greater age, larger size and progression of the tumour. The Bcl-2 protein was high in the normal thyroid, in the adenomas and in the carcinomas, decreasing in correlation with histological dedifferentiation, and totally disappearing in the anaplastic carcinomas. In medullary carcinomas its disappearance was correlated with mortality. The intense expression of the p21 RAS protein in papillary carcinomas is statistically correlated with advanced clinical studies. Conclusions. The differences in the proliferative rate between adenomas and follicular carcinomas can be of help in differential diagnosis. The p53 manifestation and the loss of the Bcl-2 expression are correlated with the histological dedifferentiation process. An intense manifestation of p21 RAS in papillary carcinomas is correlated with tumoural progression.