Endocrine Abstracts

Introduction

Differentiated thyroid cancer (DTC) is a rare disease (1%), and usually has good prognosis if well treated. However, the percentage of mortality due to this cancer is about 0.5%. Moreover, 5 to 27%of patients treated for DTC suffer from regional recurrence. Therefore, many research tried to identify predective factors for the survival, relapse and progression of this cancer.

Purpose

The aim of our study was to identify the histopathologic characteristics considered as bad prognosis signs.

Methods

This is a descriptive retrospective study for patients who had DTC and were treated either in the nuclear medicine departement or the ear, nose and throat (ENT) departement in Hbib Bourguiba hospital, Sfax, Tunisia.

Results

A total of 115 consecutive cases of DTC were reported. The median age at diagnosis was 40 years (13-83 years). Sex ratio was 5.38 (97/18). The cases included classical papillary thyroid cancer (PTC) in 88.7% and follicular thyroid cancer (FTC) in 11.3%. Total thyroidectomy was performed on all our patients : central and/or lateral neck dissection in 95.7%of patients, and radioactive iodine ablation in all the cases. Additional therapies were administered to 10 patients. A 10-year period follow-up, showed that 78.4%of patients had excellent response. Disease-free survival (DFS) was described in 81.1% of PTC and 58.3%of FTC, but differences were not statistically significant (P = 0.075). Unique tumor had better prognosis than multiple tumors : 84.9% versus 68.6%. A more than 4 cm tumor size had statistically more risk of relapse with P = 0.006. Patients with intact tumor capsule had 87.4%of DFS versus 67%in case of tumor capsule invasion (P = 0.039). In small tumors limited to the thyroid, the pourcentage of DFS was 83.3%versus 31.1%in tumors with extrathyroidal invasion. Tumor necrosis was significantly associated with bad prognosis with DFS pourcentage of 42% (P = 0.013). Finally, we noted that patients with more than 5 nod lymph involvement had a very bad prognosis (P < 0.0001). However, the affected lymph node territory had no statistically significant difference (P = 0.112).

Conclusion

Differentiated thyroid cancers account for 0.5–1% of all cancers and are usually of good prognosis. It depends on a number of factors. Some of these factors are of controversial therapeutic importance. As a result, several prognostic evaluation systems have been developed (EORTC, AMES). But not all of these factors are unanimously accepted and no international scores have been adopted.