Patterns of failure in differentiated carcinoma of the thyroid based on risk groups

Background. Risk-group stratification based on prognostic factors is well established in differentiated carcinoma of the thyroid gland. Patients in the low-risk group have an excellent prognosis, whereas there is significant mortality associated with the high-risk group. The purpose of this paper is to analyze the patterns of treatment failure in the various (local, regional, distant, and associated mortality) risk groups. Methods. In a retrospective review of e consecutive series of 1038 previously untreated patients with differentiated carcinoma of the thyroid during a period of 55 years, various prognostic factors and risk groups were analyzed. Significant prognostic factors were patient's age, presence of distant metastasis, extrathyroid extension, size, and grade of the tumor. Based on these factors, patients were divided into low- (39%), intermediate(39%), and high- (22%) risk groups. Results. The overall treatment-failure rates in the low-, intermediate-, and high-risk groups were 13%, 26%, and 50%, respectively, whereas the mortality rates in the same groups were 1%, 10%, and 33%, respectively. Conclusions. The overall incidence of recurrence rate in the low-risk group is only 13%, compared with 50% in the high-risk group. The incidence of distant metastasis in the low-risk group is only 2%, compared with 34% in the high-risk group. The understanding of the patterns of treatment failure in different risk groups reaffirms the need to direct treatment strategies based on individual risk groups and intraoperative findings.