endocrine and metabolic disorders
Thyroid Cancers
Radiation Induced Thyroid Cancer
Thyroid tumors develop in people whose thyroid is exposed to large amounts of environmental radiation, as occurs as a result of atomic bomb blasts, nuclear reactor accidents, or incidental thyroid irradiation due to radiation therapy. Tumors may be detected 10 years after exposure, but risk remains increased for 30 to 40 years. Such tumors are usually benign; however, about 10% are Papillary Thyroid Carcinoma . The tumors are frequently multicentric or diffuse. Patients who had thyroid irradiation should undergo yearly thyroid palpation and ultrasonography. A thyroid scan does not always reflect areas of involvement. If ultrasonography reveals a nodule, fine-needle aspiration biopsy should be done. In the absence of suspicious or malignant lesions, many physicians recommend lifelong TSH-lowering doses of thyroid hormone to suppress thyroid function andthyrotropinsecretion and possibly decrease the chance of developing a thyroid tumor. Surgery is required if fine-needle aspiration biopsy suggests cancer. Near-total or total thyroidectomy is the treatment of choice, to be followed by radioiodine ablation of any residual thyroid tissue if a cancer is found (depending on the size, histology, and invasiveness). 