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Thyroid cancer is a cancer originating from follicular or parafollicular thyroid cells. These cells give rise to both well-differentiated cancers (i.e., papillary and follicular) and anaplastic thyroid cancer. The second cell type, the C or parafollicular cell, produces the hormone calcitonin and is the cell of origin for medullary thyroid carcinoma (MTC). The most effective management of aggressive thyroid cancers is surgical removal of thyroid gland (thyroidectomy) followed by radioactive iodine ablation and TSH-suppression therapy. Chemotherapy or radiotherapy may also be used in cases of distant metastases or advanced cancer stage.〔http://www.mayoclinic.com/health/thyroid-cancer/DS00492/DSECTION=treatments-and-drugs〕 Five year survival rates are 97.8% in the United States.〔(【引用サイトリンク】url=http://seer.cancer.gov/statfacts/html/thyro.html )〕 ==Signs and symptoms== Most often the first symptom of thyroid cancer is a nodule in the thyroid region of the neck.〔Hu MI, Vassilopoulou-Sellin R, Lustig R, Lamont JP. ("Thyroid and Parathyroid Cancers" ) in Pazdur R, Wagman LD, Camphausen KA, Hoskins WJ (Eds) (Cancer Management: A Multidisciplinary Approach ). 11 ed. 2008.〕 However, many adults have small nodules in their thyroids, but typically under 5% of these nodules are found to be cancerous. Sometimes the first sign is an enlarged lymph node. Later symptoms that can be present are pain in the anterior region of the neck and changes in voice due to an involvement of the recurrent laryngeal nerve. Thyroid cancer is usually found in a euthyroid patient, but symptoms of hyperthyroidism or hypothyroidism may be associated with a large or metastatic well-differentiated tumor. Thyroid nodules are of particular concern when they are found in those under the age of 20. The presentation of benign nodules at this age is less likely, and thus the potential for malignancy is far greater. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thyroid cancer」の詳細全文を読む スポンサード リンク
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