Questions you may have about Medullary Thyroid Cancer

Understanding the Disease

These are common questions that patients have about understanding medullary thyroid cancer (MTC). These questions have been answered and reviewed by MTC experts.
What is calcitonin, and what role does it play in MTC?
Calcitonin is a hormone that is involved in calcium metabolism. It is secreted by C cells, which are the cells in the thyroid from which medullary thyroid cancer arises. Calcitonin is a sensitive and specific marker for the presence of MTC and can be measured in the blood. Your care team will measure the calcitonin level in your blood to help determine whether disease is present, whether the disease has grown, and what the response to therapies has been.
How are calcitonin levels used?
Your care team can use calcitonin levels in two ways. The first way is looking at the individual absolute amount of calcitonin. The level can suggest the amount of disease that is present and give an idea of whether the disease is located only in the neck or has spread outside the neck to other areas of the body. This value can sometimes guide what type of imaging should be used to look for disease. The second way is to look at trends in calcitonin over time; if the level goes up quickly or drastically, there may be more concern that the disease is growing. See “What is calcitonin doubling time?” for further detail.
What is Calcitonin Doubling Time (CDT), how is it calculated, and how is it used?

Calcitonin doubling time is the amount of time (usually in either months or years) that it takes for a patient’s calcitonin to double in amount. It is calculated using levels of calcitonin in the blood over multiple time points, usually using no less than two years of levels to calculate. The shorter the doubling time, often the faster the MTC is thought to be growing. Of note, calcitonins should only be used in CDT or compared to one another if they were performed at the same lab.

What factors can affect my calcitonin levels?
A non-fasting state will increase calcitonin. For that reason, it is recommended that patients get their calcitonin done in a fasting state or around the same time every day. Also, for about 2 days prior to the blood draw, patients should avoid high caloric foods or liquids (ex. beer or wine). Additionally, contrast can cause the calcitonin to go up. It is recommended getting blood drawn prior to any IV contrast CT. Additionally, lab errors can occur where the lab held onto the specimen for too long and did not keep it on ice; that leads to degradation of the specimen, and then calcitonin can be elevated.
Does my calcitonin level correlate with the amount of disease I have?

Typically, calcitonin level does correlate with extent of disease where, when calcitonin is over 500, there is a higher chance that there is disease outside of the neck like lungs, liver, or bones. However, there are times when the medullary thyroid cancer does not produce calcitonin effectively, in which case the calcitonin may seem lower even in the setting of distant metastasis. In this situation, we also look at the CEA level which is typically much lower than the calcitonin level, but if the CEA is somewhat similar to the calcitonin level, that might suggest a dedifferentiated MTC. The higher the calcitonin level, usually the more disease is present.

What is CEA, and what does it mean for an MTC patient?
Carcinoembryonic antigen (CEA) is a substance often secreted by MTC cells. Similar to calcitonin, your care team may use its absolute amount and change over time to help predict disease behavior. Unlike calcitonin, it is not specific to MTC and is produced by a number of cancers such as colon and rectum cancers.
How do I know the “Stage” of my MTC?
Cancer staging is the process of figuring out how much cancer is in a person’s body and where it is located. A cancer stage can help determine what kind of treatment works best and can help predict the course that the cancer will take.

Stage is determined by the extent of disease seen on imaging and pathology. Your physician should be able to tell you your stage of disease.

Staging is described through the TNM classification system and is made up of looking at the primary tumor (described as the T), whether the disease has spread to the lymph nodes (described as the N), and whether the cancer has spread to distant parts of the body (described as M).

Does MTC treatment differ by stage?
Early-stage MTC is often treated by surgery to remove the primary tumor and surrounding lymph nodes. Some advanced stage MTC that involves distant metastasis also involves surgery to remove the primary tumor. Other times advanced disease requires other treatment in the form of systemic therapy or radiation.
What is an MTC Center of Excellence?

A “center of excellence” is an institution that has health care providers with extensive experience in treating MTC. There is not a certification for an MTC center of excellence; however, it is a place that treats a high number of patients with this rare disease.

What kind of health care provider should I see for MTC?
Initially, the most important characteristic of your provider is to have adequate knowledge of MTC. You may need different health care providers during your journey including a surgeon, endocrinologist, medical oncologist, and genetic counselor. Important for all of these providers is that they understand MTC.
Can MTC be prevented?
MTC occurs sporadically 75% of the time, meaning that the tumor develops in an individual who does not have an inherited change in their genes that increases their risk for cancer. MTC cannot be prevented in this setting. MTC occurs in a hereditary setting in 25% of the cases, in which a mutation or change in the RET gene is passed from parent to child that predisposes an individual to develop MTC. In a patient who is predisposed to developing a cancer, if the thyroid is removed before MTC develops, MTC can be prevented
Will I ever be considered cured?

Patients are considered cured if they have no evidence of disease on imaging or in evaluation of the tumor markers in their blood. However, we continue to follow such patients because recurrence is always possible in the future.

Other Questions to Ask Your Doctor

  • What type of thyroid cancer do I have?
  • Who will be part of my health care team, and what does each member do?
  • How do individuals in training fit into my care?
  • What is the best way for me to remain in contact with my care team?
  • Can you explain my pathology report, imaging, or laboratory test results to me?


These are common questions that patients have about genetics related to medullary thyroid cancer (MTC). These questions have been answered and reviewed by MTC experts.
Why should I consider genetic testing and/or counseling?
A patient who has medullary thyroid cancer has an approximately 25% chance that their disease is hereditary in nature. Having hereditary MTC means that they have a gene mutation (or change) that can be passed from generation to generation that causes the cancer to occur. In the case of hereditary MTC, the gene is called RET. This same gene mutation/change can also cause other diseases including primary hyperparathyroidism and pheochromocytoma. Knowing that the patient has this gene mutation/change allows us to monitor for development of these diseases. Additionally, if the patient has hereditary MTC, then their family members, especially first-degree relatives (parents, siblings, children), should be tested to see whether they have the mutation and are at risk for developing medullary thyroid cancer and these other diseases.

To find a genetic counselor in your area, you can visit

Why would I be tested for pheochromocytoma/and or primary hyperparathyroidism? Do I need to get a blood or urine test for this?

If a patient has an RET gene mutation/change that causes hereditary medullary thyroid cancer, they also are at risk for developing pheochromocytoma and primary hyperparathyroidism. Therefore, they would be tested annually for these two diseases. Usually this testing is a blood test but sometimes can be a urine test.

What is the difference between germline and somatic mutations?

All tumors and cancer are caused by changes in genes. These changes are called mutations. In patients with an inherited disease like MEN2, the disease-causing mutation is in every cell of the body when they are born, and this is called a germline mutation. Sometimes mutations occur only within the tumor or cancer itself. These mutations are called somatic mutations and are acquired over time. Somatic mutations are not present from birth nor can they be passed down to the next generation. Germline mutations are typically detected through a blood or saliva test, while somatic mutations are detected by evaluation of the tumor tissue itself.

If I have MEN2, does that mean I have MTC too?
If a patient carries a germline RET mutation that can cause medullary thyroid cancer, they are at risk for developing the disease. The thyroid may be able to be removed prior to them developing the disease, in a procedure often called a prophylactic thyroidectomy. Some types of germline mutations cause medullary thyroid cancer to occur early in people’s lives while other mutations are more associated with MTC developing later in life. The majority of patients with MEN2 who do not undergo a prophylactic thyroidectomy will develop medullary thyroid cancer during their lifetime.
Are there ways to prevent passing this mutation to my future children?

25% of MTC is hereditary (runs in families). The first step is to determine whether you have a hereditary cancer syndrome through genetic testing. Individuals with a known hereditary cancer syndrome, such as MEN2, may choose to use preimplantation genetic diagnosis, or PGD, to ensure they won’t pass the hereditary syndrome on to their children. PGD is the process of performing genetic testing on embryos for a known hereditary cancer syndrome and only using embryos that do not have the hereditary syndrome through the process of in-vitro fertilization (IVF).

If I get genetic testing, will this affect my insurance coverage?
There was a federal law passed in 2008 called the Genetic Information Nondiscrimination Act (GINA) that protects most individuals from both employment and health insurance discrimination based on genetic test results. However, this law does not provide those same protections to life, long-term care, and disability insurance. If you have concerns about if or how genetic testing will affect any of your insurance coverage, it is important that you have the opportunity to address those concerns prior to having genetic testing.


These are common questions that patients have about treatment options for medullary thyroid cancer (MTC). These questions have been answered and reviewed by MTC experts.

General Treatment Questions

General Treatment Questions to Ask Your Healthcare Provider

  • What are my treatment options?
  • What long-term side effects or late effects are possible based on the cancer treatment I received?
  • What is the goal of each treatment? Is it to eliminate the cancer, help me feel better, or both?
  • Who will be leading my overall treatment?
  • What experience do you have in treating this type of thyroid cancer?
  • Do I need to make a treatment decision right away?
  • What will we do if the treatment doesn’t work or if the cancer recurs?
  • Where can I get a second opinion?

Questions About Surgery

Can MTC be treated by surgery?
Surgical cure of MTC is sometimes possible when the disease is limited to the thyroid and surrounding lymph nodes. Even when disease has spread outside of these areas, we often surgically remove the primary tumor to prevent problems associated with continued growth of the tumor within the neck.
If thyroid surgery is recommended, how much of my thyroid gland will be removed?
If the diagnosis of MTC is made prior to surgery (by an FNA or other biopsy), then the usual treatment would be to remove the entire thyroid. If the diagnosis of MTC is made after half of the thyroid has been removed, sometimes that is adequate treatment. Other times, the rest of the thyroid may need to be removed along with additional lymph nodes.
Will lymph nodes be removed as well?
If the diagnosis of MTC is known prior to surgery, then removal of the lymph nodes in the central neck surrounding the thyroid should occur at the initial operation. Additionally, lymph nodes in the areas at the sides of the neck (called the lateral neck) may also need to be removed if they contain cancer.
What type of scar can I expect?
The length of the scar is often determined by the extent of the operation. A surgery to remove the thyroid and the surrounding central neck lymph nodes may require a small central incision, while an operation that includes removing the lateral neck lymph nodes may require a longer incision.
How experienced in MTC should the surgeon for this type of surgery be?

In general, improved outcomes have been found in patients seen by surgeons who operate on the thyroid frequently. Because MTC is rare, it is also helpful for the surgeon to have familiarity with MTC specifically.

What tests would I need before surgery?
  • A comprehensive neck ultrasound to include the thyroid bed and the lateral neck compartment
  • Tumor markers including serum calcitonin and CEA
  • Additional imaging based on extent of disease suspected
  • Evaluation of vocal folds if there is concern for tumor involvement
Will surgery cause hypothyroidism? If so, how do you treat hypothyroidism?

If your entire thyroid is removed, you will be hypothyroid and will need thyroid hormone replacement in the form of daily medication.

How can I expect to feel differently without my thyroid?

Sometimes patients report feeling some fatigue and experience challenges with weight changes.

Why is preserving the parathyroid during surgery important?
The parathyroid glands control our calcium levels in our bloodstream and thus are important organs. They are located close to the thyroid gland and are at risk of not functioning after thyroid surgery.
Do I need to get my tissue tested for mutations after initial surgery?

Testing tissue for mutation is usually reserved for when additional therapy is planned for advanced diseases.

Will I only have one surgery in my neck for MTC?

Ideally, you would only have one operation within the neck. However, because MTC can recur, additional operations may be necessary. Knowing the diagnosis prior to surgery and performing complete preoperative imaging allows for the best chance of an optimal first surgery.

What can my healthcare team learn from my pathology?

Your team can learn about the extent your disease has spread which can help with staging and determining how the disease will behave.

Do I need to have surgery to understand my disease stage?

Not necessarily, as sometimes imaging can be used to determine if there is disease in the lymph nodes in the neck, and it is often used to determine if there is disease that has spread elsewhere in the body.

See How do I know the “Stage” of my MTC? in the Understanding the Disease section above for more information about MTC staging

What are potential common complications of surgery?
One potential complication of surgery in the neck relates to the various nerves encountered during the operation. The recurrent laryngeal nerve innervates our vocal folds and if compromised, can affect quality of voice and potentially airway blockage. Other nerves affect our shoulder movement and ability to breathe. If all four parathyroid glands do not work after surgery, you could have temporary or permanent symptoms related to low calcium (numbness and tingling around the mouth or fingertips or cramping of the extremities) and the need for calcium replacement.

Questions About Hormone Replacement Therapy

When do I need to start taking thyroid hormone pills? If so, for how long?
Thyroid hormone replacement is required after a total thyroidectomy and occasionally after a partial thyroidectomy. It’s recommended to initiate thyroid hormone replacement pills the day after a total thyroidectomy. This is a lifelong hormone replacement therapy required for maintenance of normal metabolism.
If I need to take thyroid hormone replacement, how often do I need my dose checked through blood tests?
Typically, after a thyroid hormone dose is initiated, we recommend checking TSH and free T4 approximately 6 to 8 weeks after a dose adjustment.
If I miss a dose, will that affect me in the long term?
Missing an occasional dose is not going to adversely affect your health. However, if you miss one or more doses per week you are not getting a sufficient amount of thyroid hormone replacement on a routine basis. Thus, if you forget a dose, it is recommended that the next day, you take 2 tablets to make up for that missed dose. In the end, it’s not recommended to do this on a routine basis, and it’s highly encouraged that you find ways to remember to take your medication daily.
What situations can interfere with thyroid hormone replacement?
Taking your thyroid hormone medication with other foods or liquids other than water may decrease the absorption of your pill and reduce your overall concentration of drug in your body. Additionally, if you take it too soon near oral contraceptive medication with estrogen or calcium or antacid or an acid reflux medication, your thyroid hormone levels may be disrupted.

In addition, diarrhea which can be problematic in MTC patients can alter the absorption of thyroid hormone into the body and require higher doses.

Other Hormone Replacement Therapy Questions to Ask Your Healthcare Provider

  • Who should I contact about any side effects of hyperthyroidism or hypothyroidism I experience? And how long should I wait?
  • Will my dose be adjusted in the future? How often?
  • Do I need to take my thyroid hormone at the same time daily?

Questions About Systemic Therapy

When do I need to be placed on systemic therapy?
Typically, systemic therapy starts when patients develop structural evidence of progression (that is, radiology imaging shows lesions are growing within 12 months) or if patients are highly symptomatic with diarrhea or Ectopic Cushing’s that is not manageable with other supportive measures. Typically, we do not recommend starting systemic therapy based only on rising tumor markers or if patients have stable or indolent disease.
What are the possible side effects of systemic treatment, in the short term and long term?
What medications are currently approved for the treatment of MTC in the United States?

Vandetanib, Cabozantinib, Selpercatinib, and Pralsetinib have been approved by the Food and Drug Administration (FDA) for the treatment of MTC in the United States.

What clinical trials are available? Where are they located, and how do I find out more about them?

Other Systemic Therapy Questions to Ask Your Healthcare Provider

  • Should I think about taking part in a clinical trial?
  • If I am on a clinical trial, can I complete the requirements locally?
  • What should I do to be ready for treatment?
  • What are some ways I can remind myself to take my pill each day?
  • What long-term side effects or late effects are possible based on the systemic treatment I receive?
  • Whom should I contact about any side effects I experience? And how long should I wait?
  • What is the chance that I will have to stop taking the drug due to side effects? What can be done to monitor and relieve the side effects?
  • Will there be dose changes while I’m on this drug?

Questions About Radiation

How does radioactive iodine differ from radiation treatment?
Radioactive iodine is given by mouth as a one-time dose that is a radioactive form of iodine that will bind to iodine receptors in the body, typically thyroid follicular cells. This is recommended for patients with differentiated thyroid cancer, most commonly papillary thyroid cancer, not medullary every cancer. It is not using ionizing radiation from an external machine directed at a certain part of the body.
Is radioactive iodine treatment recommended?

Radioactive iodine is not recommended for MTC as medullary thyroid cancer cells do not have iodine receptors and will not absorb the radioactivity and be treated by it.

In what locations of the body is radiation recommended?

At times, external beam radiation may be recommended to areas of focal progression, such as a bone metastasis or a lung metastasis that is near an airway. Rarely, if there is invasive disease in the neck involving the wall of the trachea or the esophagus, radiation may be recommended for focal treatment to prevent progression in that region in the future. However, external beam radiation therapy to the neck must be considered with significant caution and only after discussion in a multidisciplinary fashion, as radiation to the neck can lead to serious side effects, as well as limit or prevent future beneficial surgery in the neck.

Radiation Questions to Ask Your Healthcare Provider

  • Whom should I contact about any side effects I experience? And how soon?

Questions About “Watch and Wait” or Active Monitoring

What is “watch and wait” or active monitoring?
As many cases of medullary thyroid cancer could remain stable or indolent for many years, a “watch and wait” or active monitoring approach is recommended where the managing provider monitors a patient at specified intervals of time with lab work and imaging to determine if there is anything progressing that warrants further treatment. For example, if calcitonin and/or CEA are rising but standard imaging such as ultrasound is not showing any changes, the managing provider may recommend checking a CT of the chest or imaging of the abdomen to look to see if there are any new areas of developing metastases.
Does watching and waiting mean my disease is not being treated?
A “watch and wait” approach is a valid form of monitoring for disease behavior. Although the patient is not technically being treated with any active chemotherapy or drug therapy, they are being monitored at appropriate intervals for structural progression that may require treatment such as surgery or chemotherapy in the future.
What is the chance that the cancer will come back? Should I watch for specific signs or symptoms?
When the medullary thyroid cancer is found and treated while it still remains within the thyroid gland and no lymph nodes were involved with thyroid cancer, the chances for cure are the greatest. However, once medullary thyroid cancer has already involved the lymph nodes at the time of diagnosis, the chances for achieving cure after a comprehensive thyroidectomy and neck dissection drop significantly. Regardless, long-term surveillance is warranted in both situations due to the chances of recurrent disease or progression of disease over time.

Often, MTC may lead to no symptoms. If there are symptoms, the most common ones are diarrhea or facial flushing. If you develop any of the following symptoms, it may suggest recurrent disease: swallowing problems, new voice changes, or back pain.

Question to Ask Your Healthcare Provider About “Watch and Wait”?

  • How will we know if the cancer has come back? What should I watch for?

Questions About Follow-up Care

Question to Ask Your Healthcare Provider About Follow-Up Care?

  • What follow-up tests will I need, and how often will I need them?
  • Will I need to stop taking thyroid hormone replacement for these tests? If so, for how long and what can I expect during this time
  • How do I get a treatment summary and survivorship care plan to keep in my personal records?
  • Who will be leading my follow-up care?
  • What survivorship support services are available to me? To my family?

Questions About Quality of Life

Question to Ask Your Healthcare Provider About Quality of Life?

  • How will this treatment affect my daily life? Will I be able to work, exercise, or perform my usual activities?
  • Could this treatment affect my ability to become pregnant or have children? If so, should I talk with a fertility specialist before cancer treatment begins?
  • If I’m worried about the costs of cancer care, who can help me?
  • What support services are available to me? To my family?
  • What would be the limitations after work?
  • What is my life expectancy with MTC?
  • What is my chance of a full recovery?