Medullary thyroid cancer (MTC) is a form of thyroid carcinoma, which grows from specialized thyroid cells called parafollicular cells, or C-cells that make a hormone called calcitonin. Calcitonin helps control bone formation and blood calcium levels.
When MTC coexists with tumors of the parathyroid gland and medullary component of the adrenal glands (pheochromocytoma), it is called multiple endocrine neoplasia type 2 (MEN2).
Approximately 25% the cancer develops in families. Familial MTC syndromes include MEN 2A, which is the most common; MEN 2B; and familial non-MEN syndromes.
Thyroid cancer typically doesn't cause any signs or symptoms early in the disease. As thyroid cancer grows, it may cause:
- A lump that can be felt through the skin on your neck
- Changes to your voice, including increasing hoarseness
- Difficulty swallowing
- Pain in your neck and throat
- Swollen lymph nodes in your neck
Medullary thyroid cancer begins in thyroid cells called C cells that produce the hormone calcitonin. Elevated levels of calcitonin in the blood can detect medullary thyroid cancer at a very early stage. Certain genetic syndromes increase the risk of medullary thyroid cancer, although this genetic link is uncommon.
Adults and children with an inherited gene mutation that increases the risk of medullary thyroid cancer are often advised to have thyroid surgery to prevent cancer (prophylactic thyroidectomy). Discuss your options with a genetic counselor who can explain your risk of thyroid cancer and your treatment options.
Fallout from an accident at a nuclear power plant could cause thyroid cancer in people living nearby. If you live within 10 miles of a nuclear power plant in the United States, you may be eligible to receive a medication (potassium iodide) that blocks the effects of radiation on the thyroid. If an emergency were to occur, you and your family could take the potassium iodide tablets to help prevent thyroid cancer. Contact your state or local emergency management department for more information.
Tests and procedures used to diagnose thyroid cancer include:
- Physical exam. Your doctor will look for physical changes in your thyroid and ask about your risk factors, such as excessive exposure to radiation and a family history of thyroid tumors.
- Blood tests. Blood tests help determine if the thyroid gland is functioning normally.
- Removing a sample of thyroid tissue. During a fine-needle biopsy, your doctor inserts a long, thin needle through your skin and into the thyroid nodule. Ultrasound imaging is typically used to precisely guide the needle into the nodule.Your doctor uses the needle to remove samples of suspicious thyroid tissue. The sample is analyzed in the laboratory to look for cancer cells.
- Imaging tests. You may have one or more imaging tests to help your doctor determine whether your cancer has spread beyond the thyroid. Imaging tests may include computerized tomography (CT) scans, positron emission tomography (PET) or ultrasound.
- Genetic testing. Some people with medullary thyroid cancer may have genetic changes that can be associated with other endocrine cancers. Your family history may prompt your doctor to recommend genetic testing to look for genes that increase your risk of cancer.
The overall survival of patients with MTC is 86% at 5 years and 65% at 10 years. Poor prognostic factors include advanced age, advanced stage, prior neck surgery, and associated multiple endocrine neoplasia (MEN) 2B.
Treatment depends on the severity of MTC and can include:
- Thyroidectomy - a removal of all or part of the thyroid gland.
- Radiation with external radiation (for inoperable cancer and sometimes postoperatively in lieu of radical neck excision) or alone (for metastasis).
- Palliative chemotherapy for locally advanced and metastatic disease.
- Adjunctive thyroid suppression, with exogenous thyroid hormones suppressing TSH production, and simultaneous administration of an adrenergic blocking agent such as propranolol, increasing tolerance to surgery and radiation.
- Vandetanib - FDA-approved indication: Treatment of asymptomatic or progressive medullary thyroid cancer in patients with unresectable locally advanced or metastatic disease
- Cabozantinib (Comentrq) - FDA-approved indication: Treatment of progressive, metastatic medullary thyroid cancer (MTC).
- Thyrotropin alpha (Thyrogen) - FDA-approved indication: As an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing with or without radioiodine imaging in the follow-up of patients with thyroid cancer.
Refer to Research Publications.