The expression and significance of P53 and P21 (WAF1/CIP1) in thyroid carcinoma

Objective: To determine the expression of P53 and P21 (WAF1/CIP1) in thyroid carcinomas and its relationship with development and prognosis of the carcinoma. Methods: 90 cases of thyroid tissues (60 thyroid carcinomas, 10 thyroid adenomas, 10 goitres and 10 normal thyroid tissues) were studied by SP immunohistochemical method. Results: Positive immunoreactivity of P53 and P21 (WAF1/CIP1) was found only in thyroid carcinomas. The positive rate of the P53 and P21 is 53.3% and 41.7% respectively. The positive-staining rates of P53 were higher in cases of undifferentiated carcinomas, positive metastasis lymph nodes or in stage III, IV than those in the cases of well-differentiated, no metastasis lymph nodes, or in stage I, II. In addition, the positive-staining of P21 (WAF1/CIP1) were lower in cases of undifferentiated carcinomas, positive metastasis lymph nodes or stage III, IV than that in the cases of well-differentiated, no metastasis lymph nodes or in stage I, II. The P21 (WAF1/CIP1) expression rate in the P53 positive group was lower than that in the P53 negative group (P<0.05). Conclusion: The expression of P21 (WAF1/ CIP1) protein in thyroid cancer is related to P53-depend pathway and P53-independent pathway, mainly the P53-depend pathway. Examination of expression of P53 and P21 (WAF1/CIP1) proteins may be helpful to judge the thyroid cancer's behavior and prognosis.