Thyroid Cancer and its Risk Factors
Jp nagar, Bengaluru Feb 5, 2018
The thyroid gland is located in the front of the neck and is responsible for producing thyroid hormone, the chemical in the body that is responsible for regulating the body’s metabolism. The pituitary gland in the brain controls the amount of hormone that is produced by secreting thyroid stimulating hormone (TSH). It affects up to 20,000 people in the U.S. every year but accounts for only 1% of new cancers that develop in the U.S. Thyroid cancer is the most common endocrine cancer.
DNA (mutations) that can alter normal thyroid cells. The genetic changes cause the cells to multiply very rapidly without the normal controls found in the rest of the gland. Any type of the cell found in the thyroid gland can mutate into a specific type of cancer. Children who had radiation exposure to the neck are at higher risk for thyroid cancer.
Diet low in iodine may increase the risk of thyroid cancer as it may enhance the risk of radiation-induced thyroid cancer.
Most often, a thyroid cancer is found when the patient feels a lump or nodule in the lower front of the neck where the thyroid is located. It is most often painless and found incidentally. An enlarged lymph node may be palpated by itself in the more lateral neck or in addition to a thyroid nodule.
Most patients have normal thyroid function at the time the nodule is discovered and have no symptoms related to hyper or hypothyroidism.
It the tumor grows, it may cause symptoms such as difficulty in swallowing food (dysphagia) if it compresses the esophagus (which is rare) or hoarseness if the recurrent laryngeal nerve that is located near the thyroid is invaded and causes vocal cord paralysis.
In children, lumps in the neck are found frequently. Most often they are not in the thyroid gland itself. Aside from swollen lymph nodes associated with infections like pharyngitis, strep throat or an ear infection, lumps should not be ignored.
Types of Thyroid Cancer
Thyroid cancers are classified based upon which cell type is involved.
• Papillary thyroid cancer: This is the most common type of thyroid cancer. It accounts for 80% of cases.
• Hurthle cell carcinoma: This is a rare variant of papillary cancer also known as oncocytic carcinoma.
• Follicular thyroid cancer: It is the second most common type of thyroid cancer. It accounts for 10% of cases.
• Medullary thyroid cancer: This thyroid cancer type arises from the C cells of the thyroid. Medullary thyroid cancers (MTC) comprise 5% of all cases.
• Anaplastic thyroid cancer: This rare cancer involves thyroid cells are very abnormal looking, accounting for 1% of all cases.
• Lymphoma: This rare cancer is most often non-Hodgkin’s B cell type.
• Sarcoma: It is very rare Thyroid cancer.
- Once a lump in the thyroid is discovered, it is important to know whether it is benign or malignant. An ultrasound is performed to assess whether there is a single nodule or whether multiple nodules are present. It can determine whether the nodule is fluid filled or solid and general appearance of thyroid looking for inflammation or irregularities and the presence of enlarged lymph nodes nearby that may represent metastatic cancer.
- Another test involves ingesting radioactive iodine, which is taken up by the thyroid gland. The gland is scanned by a Geiger counter-type of apparatus that determines how much radioactive iodine has been taken up by the gland and any thyroid nodules. If the nodule picks up much of the iodine, it is referred to as a "hot nodule." Such nodules are rarely cancerous. Nodules that take up little to no iodine are referred to as "cold nodules."