In the previous article of ENT Weekly, we discussed the generally benign nature of thyroid nodules. The most common method to rule out the many types of thyroid cancer is fine needle biopsy, giving patients peace of mind. On the other hand, results may return positive for cancer, and this week, we will look into differentiating the various types of thyroid cancer and their treatment options.
Before we dive in, it is important to remember that although the word “cancer” has the connotations of end-of-life decisions and death, thyroid cancer is one of the most treatable types of the disease. Compared to other cancers, such as breast or skin cancer, thyroid cancer has a five year survival rate of 97.9%. With adequate follow-up and social support, thyroid cancer can be defeated.
Image Source: Science Photo Library – SCIEPRO
Thyroid cancer originates in the follicular or parafollicular cells, which make up the thyroid. Various studies have correlated thyroid cancer with a number of environmental and genetic predisposing factors, but uncertainty remains with identifying definitive causes.
To classify thyroid cancer, pathologists examine biopsy samples under the microscope. The following are the 4 major variants, with descending degrees of prevalence:
- Papillary thyroid cancer (75% to 85% of cases), which disproportionately affects women
- Follicular thyroid cancer (10% to 20% of cases)
- Medullary thyroid cancer (5% to 8% of cases), which targets the parafollicular cells and is usually an indicator of multiple endocrine system level cancers
- Anaplastic thyroid cancer (<1-2% of cases)
For most cases of thyroid cancer, otolaryngologists (ear-nose-throat doctors) will recommend removal of the thyroid, also known as a thyroidectomy. If the cancer is isolated on only one side of the thyroid, a thyroid lobectomy may be performed, in which only one side is removed. In cases where metastases, or spread of cancer, is a concern, the surgeon may elect to do a radical neck dissection, in which lymph nodes are removed from the neck with the thyroid. After successful removal, radioactive iodine uptake is used to ensure total destruction of cancer cells. As the thyroid is the only organ in the body that uses iodine (for hormone production), there is usually very minimal collateral damage to other cells.
With radioactive iodine and the high selectivity of cell treatment, most thyroid cancers are completely eliminated and never recur. An exception to this statement is anaplastic thyroid cancer, which has a poor prognosis and less than 7% survival rate due to its aggressive and rapidly spreading nature.
With that in mind, it is always important to have routine physicals to screen for thyroid abnormalities! Stay tuned for next week when we look at some complications that may arise after thyroidectomy.
Feature Image Source: Justin Chin
