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Thyroid cancer is a malignant disorder with a wide spectrum of disease ranging from indolent papillary microcarcinoma to fatal anaplastic carcinoma. The most common type is papillary carcinoma followed by follicular carcinoma. Most surgeons agree that total thyroidectomy followed by radioactive iodine therapy and TSH suppression is needed in the majority of patients with well－differentiated thyroid carcinoma. In some patients with papillary microcarcinoma, a less aggressive approach may be advised(lobectomy or isthmusectomy) because of its favorable long－term prognosis. The central compartment node dissection is routinely performed in thyroid cancer whether or not clinically involved, but the lateral neck node dissection is done only in patients with clinically positive. Medullary carcinoma is far less common, but has a worse prognosis. This type of cancer requires total thyroidectomy plus central and lateral neck node dissection. Anaplastic carcinoma is the least common and the most aggressive thyroid cancer. In most cases the cancer spreads very early to vital neck structures and metastasizes extensively to cervical lymph nodes and distant organs. Even with aggressive therapy, almost all patients are associated with a fatal outcome within 6 months after diagnosis. For localized thyroid lymphoma, externalbeam radiotherapy has been the standard practice, and for advanced tumor, the radiotherapy preceded by chemotherapy has been recommended. For locoregional recurrence, complete resection should be attempted in all patients and high－dose radioactive iodine or external－beam radiotherapy should be added to improve the survival rates.
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