What is the thyroid?
The thyroid is a butterfly-shaped gland in the neck, just above the collarbone. It consists of the right and left lobe joined by a thin section called the isthmus. The thyroid helps set the body’s metabolism rate. An inactive thyroid results in a person gaining weight and feeling tired all the time; on the other hand, an overactive thyroid makes a person lose weight, speeds up the heart rate and makes him or her very sensitive to heat.
Types of thyroid cancer
Thyroid cancer is a cancer that starts in the thyroid. Four types of thyroid cancer have been identified: papillary, follicular, medullary, and anaplastic.
(a) Papillary carcinoma is the most common, and usually affects one side of the thyroid. Though less aggressive, it can spread to the lymph nodes but its cure rate is very high. Papillary carcinoma usually affects women of child-bearing age.
(b) Follicular carcinoma is the second most common type of thyroid cancer. It doesn’t usually spread to the lymph nodes, but may invade the arteries and veins of the thyroid gland. This type of cancer is more common in older people but the long-term survival rate is high.
( c) Medullary carcinoma is the third most common type of thyroid cancer. It differs from papillary and follicular cancer as it arises from non-thyroid cells (called C cells) that are present in the thyroid gland. It can spread to the lymph nodes, lungs and liver. Medullary carcinoma can run in families but cure rate is moderately high.
(d) Anaplastic carcinoma is the rarest but most serious thyroid cancer. It is more common in men aged over 65, and can spread to other organs of the body. Survival rate is low as it does not respond to radioiodine therapy.
Some of the symptoms that may indicate thyroid cancer are the following:
* A lump or swelling in the front of the neck or in the area of the Adam’s apple.
* Enlargement of the neck
* Enlarged lymph nodes in the neck
* Changes in voice or difficulty speaking
* Problems with swallowing
* Pain in the neck or throat
* Persistent or chronic cough not due to illness
* Asymmetry in the thyroid (swollen on one side, normal on the other)
* Nodules that cause the wind pipe to go to one side of the neck
However, the above are not sure signs of thyroid cancer. An infection or a non-malignant tumour can also cause these symptoms. Only a doctor can diagnose the problem.
Thyroid cancer is not contagious but people with certain risk factors are more likely to develop the disease:
(a) Insufficient Iodine in the Diet
Iodine, a nutrient, is necessary for the thyroid to produce thyroid hormone. In countries where the diets are lacking in iodine, thyroid cancer is more prevalent.
(b) Exposure to Radiation
People exposed to high radiation have a higher risk of developing thyroid cancer. Repeated exposure to routine x-rays such as dental x-rays and chest x-rays may even be harmful. Also, exposure to radioactive fallout (such as leaks at the Fukushima Daiichi nuclear power plant in Japan) is a risk factor for thyroid cancer in both children and adults.
An estimated 20% of patients with medullary carcinoma develop the disease due to hereditary factors.
Women are two to three times more likely than men to develop thyroid cancer.
Majority of thyroid patients are above 40 years old. Anaplastic thyroid cancer is most common in people over the age of 65.
Depending on the type and stage, thyroid cancer may be treated with surgery (either partial or total removal of the thyroid), radioactive iodine (to destroy thyroid cancer cells anywhere in the body), hormone treatment, external radiation, or chemotherapy. Some patients receive a combination of treatments.