Thyroid cancer arises from a butterfly-shaped gland located at the front of the neck known as thyroid gland situated just below the larynx (voice box) and on top of the central trachea (windpipe).It produces hormones that play a key role in the digestive system, keep the nervous system working normally, control body temperature, heart rate, blood pressure, and breathing.
Sometimes, the cells of the thyroid can mutate and begin growing in an unregulated and abnormal manner leading to thyroid cancer.
TYPES
There are four main types of thyroid cancer: papillary thyroid cancer, follicular thyroid cancer, medullary thyroid cancer, and anaplastic thyroid cancer.
Papillary thyroid cancer is the most common type of thyroid cancer, accounting for roughly 85 percent of all diagnoses, according to the National Cancer Institute. If diagnosed early, the cure rates for this type of thyroid cancer are high.
Follicular thyroid cancer is the second most commonly diagnosed type of thyroid cancer, accounting for approximately 10 percent of diagnoses. It begins in follicular cells and usually grows slowly. This type of cancer is also highly treatable if diagnosed early enough.
Medullary thyroid cancer develops in the thyroid’s C cells, which make a hormone called calcitonin that helps maintain calcium levels in the blood. This rare cancer occurs in nearly everyone with a certain gene mutation. Blood testing can usually detect the presence of this altered gene.
Anaplastic thyroid cancer is a very rare and aggressive type of thyroid cancer that usually affects those over age 60. This type of cancer grows and spreads quickly, and is difficult to treat.
Known Risk Factors for Thyroid Cancer include:
- Exposure to ionizing radiation
This is the strongest risk factor for thyroid cancer. The younger you were when exposed, the higher your risk of developing thyroid cancer. Possible sources include radiation therapy, which is often used to treat childhood cancers, nuclear accidents and weapons, and diagnostic imaging tests, such as X-Ray and MRI scans.
- Non-cancerous thyroid conditions
A history of benign thyroid conditions, such as nodules, goiter, or thyroiditis, is linked to an increased risk of thyroid cancer.
- Family history of thyroid cancer
If there is a history of thyroid cancer in your immediate family, this puts you at higher risk of developing it.
- Hereditary conditions
Some rare hereditary conditions are linked to an increased risk of thyroid cancer, including MEN2 (as mentioned in About Thyroid Cancer), Cowden syndrome, and Werner syndrome.
SIGNS & SYMPTOMS
A lump in the front, lower part of the neck, hoarseness or change in the quality of voice, difficulty in swallowing, difficulty in breathing, swollen lymph nodes in the neck, a cough that doesn’t go away and is not due to a cold, a sore throat that is not due to a cold, neck pain that doesn’t go away are one of the common presentation of thyroid cancer.
DIAGNOSIS
Some necessary diagnostic steps like health history, including past exposure to ionizing radiation and family history of thyroid cancer; blood tests, in order to measure thyroid hormone levels; or an ultrasound, to investigate the nodules or to guide a needle in order to obtain a biopsy can help in diagnosis.
FNAC(Fine needle aspiration cytology) is a simple test which can not only confirm thyroid cancer but also can tell us the type of thyroid cancer. Your doctor will advise blood tests to assess the level of thyroid hormone. Some blood tests like Serum thyroglobulin and calcitonin are helpful for treatment and follow up of certain types of thyroid cancer.
Among the imaging/radiological tests,Ultrasonography of neck is the most commonly used method to detect any lump or nodule in thyroid gland.It also helps to determine the lymph node spread. CT/MRI is required at advanced stage disease where there is suspicion of involvement of food pipe(esophagus),wind pipe (trachea) or major vessels of the neck.
TREATMENT
Surgery is the mainstay of therapy for thyroid cancer. Lots of controversies are there regarding extent of surgery and management of neck.
Total/Near total thyroidectomy is done for any thyroid cancer larger than 1 cm. Lobectomy i.e removal of only one lobe is performed rarely now-a-days only in case of smaller tumors<1 cm. Neck dissection is performed only if enlarged lymph nodes are found on neck examination or on USG.
Radioactive iodine ablation(RAI) therapy is used to treat any residual disease in case of PTC/FTC. It is also used prophylactically in PTC/FTC in case of high risk features found on final biopsy report post surgery. However RAI is not helpful in Medullary or Anaplastic variety.
Life long thyroid hormone replacement therapy in case of Total thyroidectomy surgery.
Radiation therapy is used in case of anaplastic thyroid cancer where surgery is not possible.
Chemotherapy and various targeted therapies has been used to treat advanced thyroid cancers as well as recurrent and metastatic thyroid cancers.
PREVENTION
Though some cases of thyroid cancer are sporadic and unpreventable, there are certain steps you can take to reduce your risk and lower your chances of developing thyroid cancer. Among them:
- Maintain a healthy body weight
Since obesity has been shown to increase risk of thyroid cancer, maintaining a healthy body weight and being physically fit can be an important prevention strategy.
- Avoid unnecessary radiation exposure
Consider the need for imaging tests, and if they are absolutely necessary, ask the doctor or technician about the possibility of a thyroid guard, which are widely available but not typically used unless requested by the patient.
- Eat vegetables and fruit
Some studies have shown that the consumption of cruciferous fruits and vegetables (such as broccoli, cauliflower, and Brussels sprouts) can reduce your risk of thyroid cancer.
- Find out if you’re at high risk
Talk to your doctor about your risk. Consider genetic testing to assess your risk, especially if you have a family history of thyroid cancer.