Well differentiated thyroid cancer.

Cancers of follicular cell origin are the most common of the endocrine malignancies. Thyroid cancers are seen with increased frequency after radiation exposure and in some familial syndromes. Interestingly, the prognosis of thyroid carcinoma is highly dependent on the age of the patient at the time of examination: several clinical staging systems facilitate appropriate treatment planning. The ability of the follicular cell to take up iodine permits the use of radioactive iodine for follow-up and therapy. After thyroidectomy and radioiodine ablation, thyroglobulin becomes a sensitive marker for the presence of recurrent or metastatic disease. Patients who are thyroglobulin-positive but radioiodine-negative or who have antithyroglobulin antibodies are a clinical challenge. Improvement in imaging studies can help in the treatment of these patients. New treatments, such as the use of agents to improve iodine uptake in follicular cell tumors, are in early clinical investigation; others are in experimental development but hold promise for the treatment of aggressive thyroid malignancies.