Thyroid cancers are especially common in patients who have received irradiation to the head and neck region for benign diseases. Well-differentiated papillary and/or follicular carcinomas are the most common types of thyroid cancer. They grow slowly and have a very good prognosis when managed with an appropriate combination of surgical and medical therapy. Other types of thyroid cancer often require more intensive therapy and follow-up. It is especially important to evaluate relatives of patients with medullary thyroid cancer.