P53 MUTATIONS IN HUMAN THYROID CARCINOMAS

Mutational changes in p53 tumor suppressor gene, located on chromosome 17p are the most frequent genetic alterations in malignant human tumo rs. In several carcinomas the tumor prognosis correlates with p53 expr ession. Most of the tumors in which p53 mutations are detectable are c haracterized by poor prognosis and low differentiation. We have studie d tumor tissue of 31 patients with thyroid carcinoma for p53 mutations (16 papillary carcinomas, 8 follicular carcinomas, 5 medullary carcin omas, 1 anaplastic carcinoma and 1 highly malignant Non-Hodgkin lympho ma). Immunohistochemistry of all 31 carcinomas revealed p53 expression in 2 papillary, 2 follicular and 1 anaplastic carcinomas. All 5 tumor s were histologically tumor staged as pT4, No, Mr. P53 mutations were detected only in 1 anaplastic carcinoma in exon 5 and in 1 papillary c arcinoma in exon 6 by PCR/SSCP amplified DNA using primers bracketing the known hot spots on either exons 4-9. In both tumors p53 expression was also revealed by immunohistochemistry. We conclude that p53 mutat ions are rarely found in thyroid carcinomas and indicate poor prognosi s.