Patterns of nodal and distant metastasis based on histologic varieties in differentiated carcinoma of the thyroid

BACKGROUND: Understanding of differentiated carcinoma of the thyroid has improved in recent years with the definition of prognostic factors and risk group analysis. We intend to review our experience of differentiated thyroid cancer in relation to the risk of nodal and distant metastasis based on various histologic subgroups. METHODS: This is a retrospective review of a consecutive series of 1,038 previously untreated patients with differentiated carcinoma of the thyroid treated over a period of 55 years. Univariate and multivariate analysis of various prognostic factors was performed. The incidence of nodal and distant metastasis was analyzed based on various histologic varieties of differentiated thyroid cancer. RESULTS: There were 337 male and 701 female patients. The various histologic subgroups included papillary (810), follicular (169), and Hurthle cell cancer (59). The cumulative risk of nodal metastasis based on histological group was 61%, 30%, and 21% for papillary, follicular, and Hurthle cell variety, respectively. The risk of distant metastasis for the same histologic varieties was 10%, 22%, and 33%, respectively. The 5- and 20-year survival for these histologic subgroups was papillary (94% and 87%, respectively), follicular (87% and 81%), and Hurthle cell tumors (81% and 65%; P <0.001). CONCLUSIONS: The incidence of nodal metastasis is highest in the papillary subgroup; however, the incidence of distant metatasis was 33% in the Hurthle cell variety. The risk of nodal and distant metastasis varies considerably based on individual histologic variety.