Pet Imaging In Thyroid Carcinoma

Thyroid cancer is the most common endocrine malignancy. It is divided in several types with papillary, folliculary and Hürthle cell cancer (also called differentiated thyroid cancer) originating from the follicular epithelial cells as the most common types (>90%). Other types are medullary thyroid carcinoma (a neuroendocrine tumor origi­nating from the calcitonin producing C-cells) (3-10%) and anaplastic carcinoma (often a dedifferentiated form of the other types) (2-10%) (Schlumberger and Pacini 2003). There is a different treatment for each of these types of thyroid cancer. In differentiated thyroid cancer the initial therapy is total thyroidectomy with or without lymph node dissection, followed by adjuvant radioactive iodine therapy. Radioactive iodine therapy with 131I can be used successfully due to the active uptake of iodine in tumor cells of thyroid origin. However, this property can be lost during dedifferentiation, which limits the use of this therapy in anaplastic carcinoma. Medullary thyroid cancer cells show no iodine uptake at all and curative options are therefore mainly limited to surgical resection of primary tumor and metastases (Sherman et al. 2005).