Medullary Thyroid Carcinoma: Causes, Symptoms, and Treatment
Medically reviewed by Achuta Uppu, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Medullary Thyroid Carcinoma?
Medullary thyroid carcinoma is usually treated by an endocrinologist, a hormone and thyroid doctor, and a surgeon who is experienced with this rare cancer. An oncologist, a cancer doctor, may also help. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is medullary thyroid carcinoma?
Medullary thyroid carcinoma, also called MTC, is cancer of the thyroid gland. It starts in cells that release a hormone called calcitonin. These are called C cells. The thyroid gland sits inside the front of your lower neck.
MTC is very rare. It makes up 1 to 2 percent of thyroid cancers in the United States. It can occur in children and adults.
Symptoms
Thyroid cancer may not cause early symptoms. It is sometimes found during a routine physical exam. MTC often begins as a small lump, or nodule, in the thyroid gland. Lymph nodes in the neck may also swell. Symptoms can include:
- Swelling of the neck.
- Hoarseness.
- Breathing problems due to narrowing of the airways.
- Cough, or cough with blood.
- Diarrhea due to a high calcitonin level.
- Flushing.
Thyroid cancer in general can cause trouble swallowing or pain when swallowing.
Causes and who gets it
The cause of MTC is unknown. Unlike other thyroid cancers, MTC is less likely to be caused by radiation to the neck given to treat other cancers in childhood.
There are two forms. Sporadic MTC does not run in families. Most MTCs are sporadic, and this form mainly affects older adults. Hereditary MTC runs in families. About 25% of cases are driven by inherited gene changes, and about 75% are acquired.
A change in the RET gene that is passed from parent to child may cause MTC. Inherited forms can be part of genetic conditions called multiple endocrine neoplasia (MEN). Risk is higher if you have a family history of MTC or MEN. A history of pheochromocytoma, mucosal neuromas, hyperparathyroidism, or pancreatic endocrine tumors also raises risk.
How doctors diagnose it
A doctor does a physical exam and asks about your symptoms and medical history. Tests that may be used include:
- A calcitonin blood test and a second blood test called CEA.
- Genetic testing.
- A thyroid biopsy, where a thin needle removes a small sample of thyroid tissue to look for cancer cells.
- An ultrasound of the thyroid and the lymph nodes of the neck.
- A PET scan.
People with MTC should also be checked for certain other tumors, especially pheochromocytoma and parathyroid tumors. All people newly diagnosed with MTC need to be screened for RET or other gene changes. Because the cancer type can be hard to diagnose, ask to have biopsy samples checked by a pathologist who has experience diagnosing thyroid cancer.
Treatment
Surgery to remove the thyroid gland and the nearby lymph nodes is the main treatment. Because MTC is uncommon, the surgeon should be familiar with this type of cancer. Further treatment depends on your calcitonin levels. A rise in calcitonin can mean the cancer is growing again.
Chemotherapy and radiation do not work very well for this cancer. Radiation is used in some people after surgery. Radioactive iodine therapy is not used to treat MTC.
For cancer that has spread, targeted drugs called tyrosine kinase inhibitors may be used. These include vandetanib, cabozantinib, and selpercatinib. Two newer drugs, selpercatinib and pralsetinib, target RET gene changes. They are not considered curative, and they may only stabilize or delay the cancer.
These drugs have side effects. They include diarrhea, high blood pressure, a heart rhythm change called QT prolongation, mouth or skin sores, weight loss, and raised liver enzymes. Surgery can also accidentally remove the parathyroid glands. After the thyroid is removed, you take thyroid hormone replacement pills.
Close relatives of people with hereditary MTC are at higher risk and should talk with their providers. Family members who have the changed RET gene may have their thyroid removed, which can decrease the chance of developing MTC.
When to see a doctor
Check with your doctor if you have a lump in the neck, trouble swallowing, pain when swallowing, or hoarseness. If hereditary MTC runs in your family, talk with your provider. A genetic test can check for the changed gene.
Call 911 or go to the emergency room if you have trouble breathing, cough up blood, faint, or have a sudden change in mental state, such as confusion.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Such a doctor can review symptoms such as a neck lump, order first blood tests or imaging, and refer you to an endocrinologist and an experienced thyroid surgeon. They can also help with follow-up care.
Common questions
Is medullary thyroid carcinoma hereditary?
Sometimes. Hereditary MTC runs in families, but most cases are sporadic, which means they do not run in families. About 25% of cases are driven by inherited gene changes.
What is the main treatment for medullary thyroid carcinoma?
Surgery is the main treatment. It removes the thyroid gland and the nearby lymph nodes.
Can radioactive iodine treat medullary thyroid carcinoma?
No. Radioactive iodine therapy is not used to treat medullary thyroid cancer.
Why do doctors check calcitonin levels?
Calcitonin is a hormone made by the C cells of the thyroid, and a blood test for it is used to diagnose MTC. Doctors also use calcitonin levels to guide further treatment.
Sources
- MedlinePlus - Thyroid cancer - medullary carcinoma
- National Cancer Institute - Thyroid Cancer Treatment (PDQ)
- American Thyroid Association - Expanding Medical Therapies for Medullary Thyroid Cancer
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
