Medullary Thyroid Cancer
What is Medullary Thyroid Cancer?
Medullary thyroid cancer is a rare type of thyroid cancer that begins in the C cells of the thyroid gland. These C cells produce a hormone called calcitonin, which helps regulate calcium levels in your blood. Unlike more common thyroid cancers that start in follicular cells, medullary thyroid cancer accounts for about 3 to 4 percent of all thyroid cancer cases.
This cancer can occur on its own, called sporadic medullary thyroid cancer, or it can run in families due to genetic mutations. About 75 percent of cases are sporadic, meaning they happen without a family history. The remaining 25 percent are hereditary and linked to genetic conditions passed down through families.
Medullary thyroid cancer tends to grow more slowly than some other cancers. Early detection makes a significant difference in treatment outcomes. The cancer can spread to lymph nodes in the neck and, in later stages, to other organs like the liver or lungs.
Symptoms
- A lump or nodule in the neck that you can feel
- Swelling in the neck area
- Pain in the front of the neck or throat
- Hoarseness or voice changes that do not go away
- Trouble swallowing
- Difficulty breathing
- Persistent cough not related to a cold
- Flushing of the face
- Chronic diarrhea in advanced cases
Many people have no symptoms in the early stages. The cancer is often discovered during routine physical exams or imaging tests done for other reasons.
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Causes and risk factors
About 25 percent of medullary thyroid cancer cases are caused by inherited genetic mutations. A mutation in the RET gene causes multiple endocrine neoplasia type 2, or MEN2, which increases cancer risk significantly. People with this mutation often develop medullary thyroid cancer at a young age. Family members of those with hereditary cases should consider genetic testing.
The remaining 75 percent of cases are sporadic with no clear cause. Risk factors include being over age 40, female sex, and exposure to high levels of radiation to the head and neck. Having a family history of thyroid disease or thyroid cancer also increases risk. Unlike some thyroid cancers, iodine deficiency does not play a role in medullary thyroid cancer development.
How it's diagnosed
Diagnosis begins with a physical exam to check for neck lumps or swelling. Your doctor may order blood tests to measure calcitonin and carcinoembryonic antigen, or CEA, which are often elevated in medullary thyroid cancer. Rite Aid offers CEA testing as an add-on through our Quest Diagnostics lab network, making monitoring accessible at over 2,000 locations nationwide.
Imaging tests like ultrasound help visualize thyroid nodules and check for spread to lymph nodes. A fine needle aspiration biopsy removes cells from the nodule for examination under a microscope. Genetic testing for RET gene mutations is recommended for all medullary thyroid cancer patients to identify hereditary cases and screen family members if needed.
Treatment options
- Surgery to remove the thyroid gland and affected lymph nodes is the primary treatment
- Targeted therapy drugs like vandetanib or cabozantinib for advanced or metastatic disease
- External beam radiation therapy in select cases where surgery cannot remove all cancer
- Regular monitoring with blood tests for calcitonin and CEA levels after treatment
- Thyroid hormone replacement medication after thyroid removal to maintain normal metabolism
- Calcium and vitamin D supplements if parathyroid glands are affected during surgery
- Genetic counseling for patients with hereditary forms to discuss family screening
- Clinical trials for new treatments when standard therapies are not effective
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- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
Medullary thyroid cancer starts in C cells that produce calcitonin, while the more common papillary and follicular thyroid cancers start in follicular cells. Medullary thyroid cancer accounts for only 3 to 4 percent of thyroid cancer cases. It has different treatment approaches and a higher likelihood of being hereditary, with 25 percent of cases linked to genetic mutations.
CEA, or carcinoembryonic antigen, is a protein that is often elevated in people with medullary thyroid cancer. Blood tests measuring CEA levels help doctors monitor the effectiveness of treatment and detect cancer recurrence after surgery. Rising CEA levels may indicate that cancer is growing or spreading, prompting further investigation.
About 25 percent of medullary thyroid cancer cases are hereditary, caused by mutations in the RET gene. These cases are linked to genetic syndromes like multiple endocrine neoplasia type 2. The other 75 percent are sporadic with no family connection. Genetic testing is recommended for all patients to identify hereditary cases and allow family screening.
Survival rates depend on the stage at diagnosis and whether the cancer has spread. When caught early and confined to the thyroid, the 10-year survival rate is over 95 percent. If cancer has spread to nearby lymph nodes, the rate drops to around 75 percent. Distant spread to other organs reduces the 10-year survival rate to about 40 percent.
Early-stage medullary thyroid cancer can often be cured with surgery to remove the thyroid gland and affected lymph nodes. Complete removal of all cancer cells offers the best chance for cure. However, if cancer has spread beyond the neck or cannot be fully removed, treatment focuses on controlling the disease and managing symptoms rather than achieving a cure.
Most patients need regular blood tests to measure calcitonin and CEA levels every 3 to 6 months after treatment. These tests help detect cancer recurrence early. Your doctor may also order periodic imaging scans to check for cancer spread. Long-term monitoring is essential because medullary thyroid cancer can recur years after initial treatment.
Advanced medullary thyroid cancer may cause chronic diarrhea due to high calcitonin levels affecting the intestines. Bone pain can occur if cancer spreads to bones. Shortness of breath or cough may indicate lung involvement. Liver involvement can cause abdominal pain or jaundice, a yellowing of the skin and eyes.
If genetic testing shows you have a RET gene mutation, your family members should be offered genetic testing. Children and siblings of people with hereditary medullary thyroid cancer have a 50 percent chance of inheriting the mutation. Early genetic testing allows for preventive thyroid removal before cancer develops, which can be lifesaving.
After thyroid removal, you will need to take thyroid hormone replacement medication daily for life. Eating a nutrient-dense diet with adequate calcium and vitamin D supports bone health, especially if parathyroid glands were affected. Regular exercise, stress management, and avoiding tobacco help support overall health and recovery.
Yes, targeted therapy drugs like vandetanib and cabozantinib are approved for advanced or metastatic medullary thyroid cancer. These medications block signals that cancer cells use to grow and divide. They are typically used when cancer has spread beyond the thyroid or cannot be removed with surgery, helping to slow disease progression.