Overview of MTC
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Medullary thyroid cancer (MTC) develops in the C cells of the thyroid gland.
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Medullary thyroid cancer is easier to treat and control if found before it spreads to other parts of the body. Sometimes it spreads before a thyroid nodule is discovered.
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The two types of medullary thyroid cancer are sporadic and familial. When the disease is familial, it may be associated with hypercalcemia and adrenal tumors (i.e., pheochromocytoma).
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Genetic testing should be done for all people diagnosed with medullary thyroid cancer. Genetic testing is considered the standard of care and is not a research test. If it is determined that the patient has familial medullary thyroid cancer, the immediate family members should be tested to determine whether there are genetic factors that can predict the development of MTC. The testing focuses on the RET protooncogene.
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In individuals with these genetic changes, including infants and children, removal of the thyroid gland before cancer has the chance to develop has a very high probability of being a preventative cure.
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Nearly 100% of patients who are found to have a mutation (an abnormal sequence in the RET protooncogene) will eventually develop MTC. The specific mutation can be used to determine when the thyroid gland should be removed.
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Medullary thyroid cancers usually make calcitonin and carcinoembryonic antigen (CEA), which can be measured by blood tests.
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Unlike papillary or follicular thyroid cancer, MTC does not have the ability to absorb iodine. Because of this, radioactive iodine treatment cannot be used to treat MTC.
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The treatment for MTC is surgical and the long-term prognosis is not quite as positive as for differentiated thyroid cancer.
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However, in recent years, newer medicines have been tested in clinical trials and show promise for treating medullary thyroid cancer that is progressing.
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Vandetanib has been approved by the FDA (U.S. Food and Drug Administration) for selected patients with medullary thyroid cancer.