Medullary thyroid cancer is actually a cancer of neuroendocrine tissue that is a part of normal fetal development. Eventually that tissue is then surrounded by thyroid tissue. Medullary is termed a “thyroid cancer” by virtue of its anatomic location only. It bears no resemblance to the “usual” thyroid cancers, papillary and follicular types.
- Medullary type represents about 5% of all thyroid cancers.
The cancer is located in what are called the “C-cells” or “parafollicular cells,” that normally secrete calcitonin, one of the hormones that regulates calcium in the body.
- We can use calcitonin as a marker of disease progress and remission.
- Sometimes these tumors make other hormones than just calcitonin, so we will check for those depending on the patient’s overall picture.
Medullary thyroid cancer can be random or hereditary. It can be associated with larger “clusters” of other hormone problems called Multiple Endocrine Neoplasias (MEN) types 2A (1 in 1.9 million) and 2B (1 in 38 million).
- When it exists in a hereditary or MEN pattern, it is almost always associated with a mutation in a gene called RET, so DNA analysis is a very important part of diagnosis.
How is Medullary Thyroid Cancer Diagnosed?
- Usually patients present with a thyroid nodule that clearly shows medullary thyroid cancer after a biopsy.
- Sometimes it is diagnosed after a patient presents with a cluster of symptoms that might look like MEN, and thyroid nodules are discovered as part of the diagnostic process.
How Do We Manage Medullary Thyroid Cancer?
- First, get baseline levels of calcitonin and CEA, which are important markers of the disease and can guide us about how extensive the cancer is.
- Second, have a DNA analysis for one of the RET mutations.
Important Genetic Considerations
- If the RET gene mutation is POSITIVE, it is FUNDAMENTAL to screen siblings and children for certain cancers and offer appropriate genetic counseling.
- The medical team is legally and ethically required to notify potentially affected family members.
Survival Rates
- Stage I: 100% survival
- Stage II: 93% survival
- Stage III: 71% survival
- Stage IV: 21% survival
- Patients whose calcitonin level goes to 0 after surgery have approximately a 97% survival over 10 years.
Follow-up and Additional Treatments
If follow-up calcitonin is not zero, the medical team will:
- Consider new imaging to check neck, liver, chest, and bones
- Potentially perform additional surgery if disease is confined to lymph nodes
- Use therapies including antibody treatments, radiation, or chemotherapy
Additional Resources
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