Thyroid carcinoma uptake of 18F-fluorodeoxyglucose in patients with elevated serum thyroglobulin and negative 131I scintigraphy.

ABSTRACT

PURPOSE: To determine if FDG-PET results can predict for outcome in thyroid cancer patients with elevated Tg and negative I-131 imaging. MATERIALS AND METHODS: We conducted a retrospective review of 76 patients who had elevated serum Tg and negative (131)I scintigraphy and who underwent FDG-PET. After FDG-PET, patients underwent neck dissection or radiation. RESULTS: The 51 patients with positive FDG-PET had a 5-year survival of 63% compared to 100% (p<0.049) for the 25 patients with negative PET. Patients with FDG-avid disease isolated to the lymph nodes had 5-year CSS of 91% compared to 32% (p=0.0033) for those with disease outside the regional lymph nodes. Twenty-nine patients with disease isolated to the regional lymph nodes underwent salvage neck dissection and 22 remain NED after 28 months. CONCLUSIONS: Negative FDG-PET with elevated Tg predicts an excellent outcome. FDG-avid disease isolated to the regional lymph nodes had a low likelihood of death due to thyroid cancer.