Clinical significance of RET/PTC and p53 protein expression in sporadic papillary thyroid carcinoma

AIMS: Rearranged during Transfection (RET)/papillary thyroid carcinoma (PTC) and p53 are two genes involved in the pathogenesis of PTC. It has been suggested that RET/PTC expression is associated with higher rates of local extension and lymph node involvement, whereas p53 mutations are more frequent in poorly differentiated and anaplastic carcinomas. In addition, experimental studies have shown that p53 activity can modify the behaviour of PTC carrying RET/PTC. The aim of this study was to investigate the expression of both RET/PTC and p53 in order to evaluate their usefulness as prognostic factors. METHODS AND RESULTS: Resected specimens of 61 cases of PTC were studied immunohistochemically using a polyclonal antibody to RET and a monoclonal antibody to p53 protein. RET/PTC expression was associated with extrathyroid extension of PTC, at diagnosis (P < 0.05). In contrast, no relationship between p53 immunoreactivity and clinical status was found. In addition, p53 expression was more prevalent among RET/PTC+ patients, and significantly influenced the relationship observed between RET/PTC and extrathyroid extension of the disease. CONCLUSION: Our results suggest that immunohistochemistry for both PTC/RET and p53 could be useful in the clinical evaluation of patients with PTC.