What is Medullary Thyroid Cancer? Causes and Symptoms
Medullary Thyroid Cancer
Medullary Thyroid Carcinoma or Cancer is a rare disease. It accounts for only 3-4 % of all 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 neuroendocrine 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 is gene mutation ( a change in genetic sequence or DNA) in the RET Proto-Oncogene. RET is a normal and necessary part of the c cell functioning , but certain mutations on the RET gene cause this gene to stay “on” and inhibit it’s 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 the overproduction of cells. At this stage, small nodules are formed although they are not cancerous at this stage but eventually may develop into MTC over a period of time.
Types of Medullary Thyroid Cancer
There are two types of MTC . They are SPORADIC( non inherited) and FAMILIAL( hereditary or inherited).
Sometimes it is also called “spontaneous MTC”. It is the most common type diagnosed in almost 75-80% of all MTC cases. A 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.
It is not that common but still has a 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 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 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, it’s better than many other types 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 the detection of thyroid nodules by the doctor.
Secondly, detection of Enlarged lymph nodes or nodes in the neck by the physician is generally larger than the 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.