Overexpression of p53 protein and MDM2 in papillary carcinomas of the thyroid: Correlations with clinicopathologic features

Expression of p53 protein and MDM2 was evaluated in paraffin-embedded tissu e from 78 patients with papillary carcinomas of the thyroid (PCT), in order to elucidate the relationship between them and their correlations with som e clinicopathologic features implicated in tumor progression. These protein s were expressed in nuclei of tumor cells, but not in non-tumor cells. Stai ning was defined as positive when 10% or more of tumor cells expressed thes e proteins. The number of cases positive for p53 protein was 21/78 (27%), a nd that positive for MDM2 was 26/78 (33%). Co-overexpression of p53 protein and MDM2 was observed in 12/78 cases (15%). A significant positive relatio nship was found between them (P < 0.01); p53-positive cases tended to be al so positive for MDM2 and vice versa. Statistical analysis revealed that ove rexpression of p53 protein significantly correlated with large tumor size ( P = 0.0271) and the presence of capsular invasion (P = 0.04). There were si gnificant positive correlations between tumor size and intrathyroidal invas ion and between tumor size and capsular invasion in PCT, suggesting that p5 3 protein overexpression is associated only with tumor progression (tumor s ize). However, we could not find any significant correlations between MDM2 expression and clinicopathologic features. Our findings suggest that overex pression of p53 protein and MDM2 in papillary carcinoma of the thyroid is a ssociated with the progression of the tumors, and that p53 may be a marker of the progression of PCT.