Medullary thyroid cancer is a type of thyroid carcinoma which starts from the parafollicular cells from which calcitonin hormone is produced. Medullary tumors make up approximately 3 percent of the total thyroid cancer cases and they are the third most common of thesehyroid cancers. This form of cancer was discovered for the first time in 1959 and around one in four cases of this type of cancer is caused by genetic inheritance. Occurrence of mutation in the RET proto-oncogene results in this condition making it to be classified as familial. When tumors of the medullary component of the adrenal glands and parathyroid gland accompany this cancer it is referred to as multiple endocrine neoplasia type 2 while it occurs alone it is termed as sporadic.
Signs and Symptoms
Certain signs and symptoms are associated with this form of cancer. Diarrhea is a major clinical symptom whereby the patient normally has flushing episodes. Both of these symptoms combined with liver metastasis are the initial indications of the manifestation of the cancer. The flushing which occurs in this type of cancer is similar to that which happens as a result of carcinoid syndrome. The itching, also known as pruritis, together with the diarrhea and the flushing are as a result of an increase in the levels of calcitonin gene-related peptide. However, the diarrhea and flushing due to carcinoid syndrome is as a result of increase in the level of circulating serotonin. This form of cancer may also result in a thyroid node together with an increase in size of the cervical lymph nodes.
This cancer originates and spreads a majority of times at the lymph nodes in the central portion of the chest, lung, liver and bone. It may also attack the lymph nodes located in the neck area. At times though very isolated cases it spreads to the skin or the brain. Though an increase in the concentration of calcitonin is not harmful, it is a useful indicator used for the testing of the any presence of a tumor. Carcinoembryonic antigen may also be used as an indicator to the presence of a tumor mass. Mutations lead to the rearrangement of the receptor tyrosine kinase protein during transfection which is majorly involved in regulation of cell development and growth. The germline mutation of this protein is responsible for almost all of these hereditary or familial cancers.
Every child of an affected parent has a 50% chance of inheriting the cancer causing genes as the cancer is inherited as an autosomal dominant trait. In others cases, sporadic version of this cancer occurs in people with no identifiable family history associated with the illness. This sporadic cancer affects older people and the disease tends to take longer before being noticed in such individuals as compared to their inheritance counterparts. This is the reason why sporadic cases are diagnosed at advanced stages of the illness.
The type of cancer is grouped into four stages of 5-year survival rate advancement. In the first stage, the survival rate is 100% while in the second stage it drops slightly to 98%. The survival rate in the third stage is 81% while in the fourth stage the rate drops drastically to 28%. Medullary thyroid cancer can be treated in a variety of ways which include surgical removal of the tumor, use of radiation treatment or the introduction of protein kinase inhibitors to block the abnormal kinase proteins which take part in the development and growth of the cancer cells.