Increased angiogenesis in papillary thyroid carcinoma but lack of prognostic importance.

Angiogenesis is important for tumor growth and progress, and the intratumor density of microvessels is a significant prognostic factor in many tumor types. The role in thyroid cancer has not been well studied, and we therefore examined a series of 128 papillary carcinomas with respect to microvessel density (MVD) and patient survival. Follow-up was obtained for all cases (median, 145 months). We found a mean MVD of 216 per mm2 (range, 35-751), and there was an average of 3.14 times more vessels in the tumors, when compared with surrounding non-neoplastic thyroid tissue. MVD was inversely related to age, tumor diameter, histological grade, and primary tumor extent. Furthermore, increasing MVD tended to be associated with improved survival (P = .056). In conclusion, our data indicate that angiogenesis is important for the development and maintenance of papillary thyroid carcinomas, although it was not identified as a prognostic factor.