Clinicopathologic significance of histologic vascular invasion in papillary and follicular thyroid carcinomas

The association of angioinvasion with tumor aggressiveness in follicular and papillary thyroid carcinoma remains unclear. This study addresses this problem focusing on clinicopathologic relevance of angioinvasion in the treatment of papillary thyroid carcinoma and follicular thyroid carcinoma.

From a university hospital database, 358 patients with papillary thyroid carcinoma or follicular thyroid carcinoma were randomly selected. Their charts were retrospectively analyzed and divided into papillary thyroid carcinoma and follicular thyroid carcinoma groups. Each group was subdivided into angioinvasive and nonangioinvasive tumor subgroups. All data were analyzed using Student's t-test, Mann-Whitney rank sum test, chi-square test, and Fisher's exact test.

There were 289 women and 69 men, ages 18 to 89 years. Papillary thyroid carcinoma (86%) was more frequent than follicular thyroid carcinoma. Most patients had nonangioinvasive tumor (90.2%). After a mean followup of 43.6 months, there were no significant differences between papillary thyroid carcinoma subgroups for local recurrence (p = 0.69), persistent elevated serum thyroglobulin (p = 0.568), and distant metastasis rates (p = 0.422). No death related to the cancer was observed in both papillary thyroid carcinoma subgroups (p = 1), except for one death resulting from a concomitant nasopharyngeal cancer. The longterm prognosis was less favorable for angioinvasive papillary thyroid carcinoma based on AJCC (American Joint Committee on Cancer staging), AMES (age, distant metastasis, tumor extent, and size), and MACIS (distant metastasis, age, completeness of primary tumor resection, local invasion, and tumor size), but the angioinvasive papillary thyroid carcinoma were larger than nonangioinvasive papillary thyroid carcinomas. The short-term clinical outcomes in both follicular thyroid carcinoma, after a mean followup of 72.3 months, were comparable in terms of local recurrence (p = 0.34), persistent elevated serum thyroglobulin (p = 1), and distant metastasis (p = 0.597). There was no death related to cancer in both follicular thyroid carcinoma subgroups (p = 1). There were no significant differences between both follicular thyroid carcinoma subgroups for longterm prognosis.

Our results indicate that angioinvasion does not adversely influence short-term outcomes or longterm prognosis in follicular thyroid carcinoma and short-term outcomes in papillary thyroid carcinoma. Angioinvasion is a postoperative pathologic finding that does not justify an ominous prognosis or drastic therapeutic measures.