Well-differentiated thyroid carcinomas: p53 mutation status and microvessel density

Risk-stratification schemes exist for well-differentiated thyroid carcinoma and include prognostic factors such as age, sex, extent of tumor, size of tumor, and presence of metastasis. Controversy continues, however, over the aggressiveness of initial surgical intervention because of anecdotal experiences of poor clinical outcomes in low-risk patients. Our objective is to determine the prognostic significance of two biologic tumor markers, the p53 gene mutation and CD34 microvessel density (MVD) count, in well-differentiated tumors of thyroid gland.

We selected 38 patients with well-differentiated thyroid carcinomas from the University of Illinois Tumor Registry. Patients had an average clinical follow-up of 10 years. Paraffin-embedded tumor specimens were available for all patients. Immunohistochemistry was performed to identify mutations of the p53 gene (Ab 1801) and to determine the MVD count (CD34).

There were significant increases in MVD counts within thyroid tumor tissue, when compared with surrounding, normal thyroid tissue. There was no significant correlation noted, however, between increased MVD and histology or recurrence rates. There was a trend toward higher MVD counts in tumor specimens of patients initially seen with metastatic lymphadenopathy. The incidence of p53 mutation expression was 28%, and there was no correlation between p53 status and histology, sex, recurrence rate, or survival.

This study supports the concept of tumor neovascularization but fails to correlate MVD with clinical behavior or pathologic features in well-differentiated thyroid carcinoma. Furthermore, we found that the p53 mutation status was not an independent prognosticator of tumor behavior in these lesions.