Survival and prognosis in Hurthle cell carcinoma of the thyroid gland

Objective: To determine factors that affect survival in patients with Hurthle cell carcinoma of the thyroid gland. Methods: Data for all cases of Hurthle cell carcinoma that occurred between January 1, 1988, and December 31, 1998, were extracted from the Surveillance, Epidemiology, and End Results database. Clinical data regarding age, sex, tumor size, primary site extension, nodal involvement, and vital status were tabulated. Patients with distant metastases were excluded, and Kaplan-Meier survival analysis was conducted. Survival data for patients with Hurthle cell carcinoma were compared with data for a control group of patients with follicular cell carcinoma matched for age, sex, tumor size, and local disease extension. Cox multivariate regression analysis was conducted to determine the effect of predictor variables on overall survival in Hurthle cell carcinoma. Results: We identified 555 cases of nonmetastatic Hurthle cell carcinoma (mean age at diagnosis, 55.9 years; women, 67.9%). The primary tumor was intrathyroidal in 83.8% of patients, whereas 11.2% had minor local extension. Mean tumor size was 3.5 cm. Mean, 5-year, and 10-year survival for Hurthle cell carcinoma was 109 months, 85.1%, and 71.1%, respectively. Mean survival for 411 matched patients with follicular cell carcinoma was 113 months, which was not statistically different from that of patients with Hurthle cell carcinoma (P=.47, log-rank test). On multivariate analysis, increasing age at diagnosis, male sex, and increasing tumor size were statistically significant predictors of poor survival; degree of primary site extension did not affect survival. Conclusions: Overall survival for Hurthle cell carcinoma is similar to that of comparably staged follicular cell carcinoma. Increasing age, male sex, and increasing tumor size substantially diminish survival in patients with Hurthle cell carcinoma.