Endocrine Abstracts

Introduction

Differentiated thyroid cancer (DTC) is the most common thyroid cancer with a relatively high survival rate. Distant metastasis (DM) is not a frequent event in DTC but has an adverse impact on mortality of patients.

Purpose

The aim of this study was to determine the most frequent metastases and their prognosis after adequate treatment.

Methods

A retrospective study of patients who had DTC metastases and were treated in the nuclear medicine departement in Hbib Bourguiba hospital, Sfax, Tunisia.

Results

A total of 26 patients had remote metastases, 19 of whom had metastasis at the time of initial diagnosis. Metastasis locations in descending frequency order were : lungs (42.3%), mediastinum (15.3%), lungs + bones (15.3%), lungs + mediastinum (7.7%), liver (7.7%), eye (3.8%) and lungs + other locations (7.7%). For pulmonary metastases, it was a miliary lung in 64.7% of cases, a single or multiple pulmonary nodule in 17.4% each. Bone metastases were unique in 2 patients and multiple in the rest. In order of frequency : Sternum : 2 cases, pelvis : 2 cases, lumbar spine : 2 cases, femur : 2 cases, shoulder : 1 case, Skull :1 case. All of our patients had radioactive iodine ablation and 8 of them had additional therapies : surgery was performed to one patient with unique mediastinum meatastases, one with both mesdiastinum ang lung metastases and 2 patients with lungs and bones metastases. Radiotherapy was performed to 4 patients (3 cases of mesdiastinum ang lung metastases and one case of lungs + bones + liver metastases). Two cases of death were reported (mediastinum metastases, lungs and bones metastases). Recovery was observed in 15 patients whilst eight had a stable health state. High thyroglobulin level remained stable in one case of lungs metastases.

Conclusion

The most common sites of metastatic differentiated thyroid cancer are the neck lymph nodes, while distant metastases typically involve the lungs, the bones, and less frequently the brain. Uncommon metastatic sites include the liver, adrenal gland, kidney, pancreas, and skin. The epidemiological aspects of thyroid metastases in rare sites are largely unknown and their identification could have a significant impact on patients management.