Endocrine Abstracts

Aim: Metastatic medullary (MTC) or iodine-negative papillary (PTC) or follicular (FTC) thyroid carcinomas present a challenge due to limited treatment options. We prospectively compared various staging procedures that may be necessary to define extent and progress of the disease.

Methods: 31 patients were included (9×MTC, 8×PTC, 14×FTC). Staging procedures included CTs of chest, abdomen, and CNS, ¹⁸FGD-PET, and bone scan. Tumor spread was defined by evidence of tumor detected in any of the methods. In MTC, tumor distribution included neck (56%), lung (100%), liver (44%), other abdominal organs (22%), CNS (22%), and bone (78%). In PTC and FTC, tumor was detected in neck (50%, 43%), lung (100%, 100%), liver (25%, 0%), other abdominal organs (25%, 7%), CNS (13%, 0%), and bone (50%, 36%), respectively. For comparative evaluation, procedures had to be performed within 2 weeks.

Results: In MTC, CTs localized all tumor masses except bone metastases (71%). PET identified 89%, 60%, 75%, and 43% of the thorax, neck, liver, and bone metastases. The bone scan detected all bone metastases. Disease progress became evident by CTs, PET, and bone scan in 86%, 86%, and 71% of patients, respectively. In PTC and FTC, both CTs and PET identified all metastases except for bone. Bone metastases were detected by CTs, PET, and bone scan in 75%, 75%, and 88% of patients, respectively. Disease progress was seen in PET (100%) and CT (90%). CNS metastases was identified by CCT only.

Conclusion: In MTC, CTs of the chest, abdomen, and CNS, combined with a bone scan are required to determine the full extent of the disease, and may therefore also be used for follow-up. In PTC and FTC, ¹⁸FDG-PET correctly identified tumor spread and progress in most patients, with the addition of CT for the CNS. A bone scan provided some additional information.