An uncommon, cancerous tumour occurring in the thyroid gland
Abnormal growths in the thyroid gland can sometimes be cancerous. Thyroid cancer is rare, accounting for only 1 in 100 of all cancers, but it is twice as common in women as men. The condition generally occurs in people who are over the age of 40, and evidence suggests that previous exposure of the neck area to radiation increases the risk. The cure rates of most types of thyroid cancer are among the highest of all cancers.
There are three main types of thyroid cancer, each arising from different cell types in the gland: papillary, follicular, and medullary. About 7 in 10 thyroid cancers are papillary, and this type of thyroid cancer spreads most often to the lymph nodes. Exposure to radiation increases the risk of developing papillary cancer. Follicular thyroid cancer is less common and may spread to the lungs or the bones. Medullary cancer of the thyroid is rare and is usually associated with multiple endocrine neoplasia, an inherited condition.
The symptoms depend on the type of thyroid cancer, but they often include:
Painless, hard lump in the neck.
The first symptom of papillary thyroid cancer may be a lump in the side of the neck due to enlarged lymph nodes.
If you develop a lump in your neck, your doctor will examine you and may arrange for a blood test to measure thyroid hormone levels. The thyroid gland may be imaged using ultrasound scanning or radionuclide scanning. Needle aspiration of the thyroid gland may be carried out to remove cells from the lump so that they can then be tested for cancer.
Thyroid cancer is usually treated by surgical removal of the whole thyroid gland. Further treatment often involves an oral dose of radioactive iodine. The radioactive iodine accumulates in the remaining thyroid tissue and destroys any cancer cells that may still be present. After treatment, you will need to take thyroid hormone drugs for the rest of your life (see Drugs for hypothyroidism). If thyroid cancer is diagnosed and treated early, the survival rate after 5 years is as high as 95 per cent.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.