What is Medullary Thyroid Cancer? Causes and Symptoms

thyroid cancer

Medullary Thyroid Cancer

Medullary Thyroid Carcinoma or Cancer is a rare disease. It accounts for only 3-4 % of all the thyroid cancers. So very often MTC Patients and their families start their MTC journey with little or no knowledge of this rare disease. Medullary Thyroid Cancer is different from common differentiated thyroid cancer such as papillary thyroid cancer which covers 80% of all the thyroid cancer cases. Their treatments are also different from medullary Thyroid cancer. However, it is easier to treat and control MTC like other types of Thyroid cancer if detected before spreading in other organs. Also, Medullary Thyroid Cancer affects people of all ages. Ranging from young children to seniors. So let us understand What is Medullary Thyroid Cancer? Causes Symptoms and Stages.

What is Medullary Thyroid Cancer?

Medullary Thyroid cancer is different from other types of thyroid cancers because it is  a neuro-endocrine tumor. This means it happens in cells that function in some ways like cells in the nervous system.

  • The cells from which MTC is derived  are hybrids, that is, they have features of both neurons and Endocrine cells
  • MTC develops in the Parafollcular C cells ( also known as ‘C’ cells, these C cells are different from thyroid follicular cells  because they do not make thyroid hormone called Thyroxine) of the thyroid gland. They have features of both neurons and endocrine cells.
  • The earliest stage , before a tumor develops appears microscopically as localized cell proliferation. So it is called “c cell hyperplasia”.
  • MTC is easier to treat however it spreads frequently before the thyroid nodule is discovered.

This article provides information about What is Medullary Thyroid Cancer? Causes Symptoms and Stages.

to know about thyroid cancer check

To know about anaplastic thyroid cancer check

What causes Medullary Thyroid Cancer?

The cause of most MTC are gene mutation ( a change in genetic sequence or DNA) in the RET Proto- Oncogen. RET is a normal and necessary part of the c cell functioning , but certain  mutation on the RET gene cause this gene to stay “on” and inhibit its turning “off”. This leads to other problems  in some cases subsequent development of MTC. The  precursor to the development of MTC is the “Nodular C cell Hyperplasia” which is due to over production of c cells. At this stage small nodule are formed although they are not cancerous at this stage but eventually may develop into MTC over a period of time.

What is Medullary Thyroid Cancer?
Medullary Thyroid Cancer

Types of Medullary Thyroid Cancer

There are two types of MTC . They are SPORADIC( non inherited) and FAMILIAL( hereditary or inherited).

Sporadic MTC

 Sometimes it is also called “spontaneous MTC”. It is the most common type diagnosed in almost 75-80% of all MTC cases. Family history of thyroid disorders is not necessary for this type of MTC. Usually, it is noticed to occur in patients over the age of 20.

Familial MTC

It is not that common but still has the percentage of 20-25% of all MTC cases. It is mostly present when certain thyroid disorder is inherited. There are again three types of Familial MTC

Multiple  endocrine neoplasia (MEN) 2A, it is an MTC syndrome that causes elevation of calcium level or possibly associated with adrenal gland tumours called Pheochromocytomas

MEN2B another type MTC Syndrome associated with pheochromocytoma( hormone secreting tumor that can occur in adrenal glands)

Familial medullary thyroid carcinoma (FMTC)

Prognosis of Medullary Cancer
What is Medullary Thyroid Cancer? Causes Symptoms and Stages

Prognosis in Medullary Cancer

Although MTC can spread to the entire body but it progresses slowly. The long term survival rate often depends on the stage of the cancer at the time of diagnosis. The long term Prognosis for this type of MTC is not as favorable for differentiated thyroid cancers such as Papillary MTC or follicular MTC. However its better than many other type of cancers and undifferentiated thyroid cancer such as Anaplastic MTC. For all type of MTC the 5 year survival rate is 85-90% and 10 year survival rate is 65-70%.

Diagnosis of MTC

First step is detection of thyroid nodule by the doctor

Secondly, detection of Enlarged lymph nodes or nodes in the neck by the physician which is generally larger than primary tumor.

Thirdly, the patient may have chronic diarrhea which usually indicates that the tumor has been spread beyond the neck, although it is quite uncommon and represents only 1-2% of MTC.

In patients with hereditary MTC the disease could be present as bumpy lips and tongue, which is specific to MEN-2B

MTC is usually painless and without any symptoms in its early stages.

Symptoms of MTC

Some symptoms that may appear are-

  • Hoarseness that has no known cause and does not go away
  • Difficulty in breathing or shortness of breath
  • Difficulty in swallowing
  • The sensation of lump growth in the neck.
  • An abnormally large lymph node (swollen) that fails to shrink even after few months.

Medullary Thyroid Cancer Staging

Staging of cancer is a general technique for describing the location and behaviour of a type of cancer.  According to American Joint Commission on Cancer, TNM is taken in consideration to understand the staging of medullary cancer here, T stands for tumour size, N stands to spread of tumour in local or regional lymph nodes and M stands for the presence of distance metastases.

Stage 1 of MTC

  • Tumor is 0.8 inch in diameter or smaller.
  • Not yet spread only present in thyroid gland.
  • No metastases is present.

Stage 2 of MTC

  • Tumor becomes slightly larger than 0.8 inch (2 cm) but less than 1.6 inch.
  • Limited to thyroid gland
  • No metastases is present.

Stages 3 of MTC

  • Tumor may be less than or larger than 4 cm
  • No metastases or regional metastases on lymph nodes may seen.

Stage 4A of MTC

  • Tumor may be anywhere from smaller than 2 cm to larger than 4 cm.
  • Extending outside the thyroid gland
  • Metastasis to lymph nodes within the neck may be present

Stage 4B of MTC

  • Larger tumor that had invaded the vertebrae of neck or encased the artery or blood vessels
  • With or without lymph node metastases
  • No distant metastasis present.

Stage 4C of MTC

  • Any tumor size or lymph node metastases may be present.
  • Presence of metastases.

From the above I hope it is clear What is Medullary Thyroid Cancer? Causes Symptoms and Stages


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