Does Hürthle cell carcinoma of the thyroid have a poorer prognosis than ordinary follicular thyroid carcinoma?

Background: Hürthle cell carcinoma (HCC) is a rare form of thyroid carcinoma and is considered an oxyphilic variant of follicular thyroid carcinoma. However, little is known about its biological characteristics or clinical behavior. We conducted a retrospective study to determine whether the prognosis of HCC differs from that of ordinary follicular thyroid carcinoma (OFC). Methods: The subjects were the 558 patients with follicular thyroid carcinoma who underwent initial surgery at our institution between 1989 and 2010 and consisted of 73 patients with HCC and 485 patients with OFC. There were 410 females and 148 males, and their median age was 51 years. A univariate analysis was conducted in relation to cumulative cause-specific survival (CSS) according to the Kaplan-Meier method for the following variables: age at the time of initial surgery, gender, tumor size, invasiveness, distant metastasis at presentation, and histological type (HCC vs OFC). Differences between groups were analyzed for significance by the log-rank test. Multivariate analysis was performed by using the Cox proportional hazard model. Results: A total of 4 patients (5.5 %) in the HCC group had distant metastasis compared with 106 patients (21.9 %) in the OFC group. Significant factors in relation to CSS in the univariate analyses were age, tumor size, and invasiveness, but there were no significant differences between the HCC group and the OFC group. Multivariate analysis showed that age, tumor size, and distant metastasis at presentation were significant factors. Conclusions: HCC does not have a poorer prognosis than OFC.