Hyperthyroidism and Thyroid Cancer
Basic Facts about Thyroid Nodules
Simply put, thyroid nodules are lumps that commonly arise within an otherwise normal thyroid gland. Often these abnormal growths of thyroid tissue are located at the edge of the thyroid gland, so they can be felt as a lump in the throat. When they are large or when they occur in very thin individuals, they can even sometimes be seen as a lump in the front of the neck. The following is a list of facts regarding thyroid nodules:
- One in 12 to 15 young women has a thyroid nodule.
- One in 40 young men has a thyroid nodule.
- More than 95% of all thyroid nodules are benign (non-cancerous growths).
- Some are actually cysts, which are filled with fluid rather than thyroid tissue.
- Most people will develop a thyroid nodule by the time they are 50 years old.
- The incidence of thyroid nodules increases with age.
- 50% of 50 year olds will have at least one thyroid nodule.
- 60% of 60 year olds will have at least one thyroid nodule.
- 70% of 70 year olds will have at least one thyroid nodule.
Three Questions about Thyroid Nodules
- Is the nodule one of the few that are cancerous?
- Is the nodule causing trouble by pressing on other structures in the neck?
- Is the nodule making too much thyroid hormone?
After an appropriate work-up, most thyroid nodules will yield an answer of no to all of the above questions. In this most common situation, there is a small- to moderate-sized nodule that is simply an overgrowth of normal thyroid tissue, or even a sign that there is too little hormone being produced.
Patients with a diffusely enlarged thyroid (called a goiter) will have what is perceived at first to be a nodule but is later found to be only one of many benign enlarged growths within the thyroid (a goiter).
Usually a fine needle aspiration biopsy (FNA) will tell if the nodule is cancerous or benign. This one test can get right to the bottom of the issue. Often an ultrasound is necessary to determine the characteristics of a thyroid nodule.
If any of the above questions are answered yes, then medical or surgical treatment is required.
Symptoms of Thyroid Nodules
Most thyroid nodules cause no symptoms at all. They are usually found by patients who feel a lump in their throat or see it in the mirror. Occasionally, a family member or friend will notice a strange lump in the neck of someone with a thyroid nodule. Another common way in which thyroid nodules are found is during a routine examination by a physician.
Occasionally, nodules may cause pain, and even rarer still are those patients who complain of difficulty swallowing when a nodule is large enough and positioned in such a way that it impedes the normal passage of food through the esophagus (which lies behind the trachea and thyroid).
Sometimes, a thyroid nodule is found because the patient is undergoing a CT scan, MRI scan, or ultrasound scan of the neck for some other reason (such as parathyroid disease, carotid artery disease, or cervical spine pain). Thyroid nodules found this way (by accident) are cancerous far less than 1% of the time.
What to Do if You Have a Nodule
Remember that the vast majority of thyroid nodules are benign. The nodule should be evaluated by a physician who is comfortable with this problem. Endocrinologists and endocrine surgeons deal with these problems on a regular basis, but many family practice physicians, general internists, and general surgeons are also adept at addressing thyroid nodules.
One of the first things a physician should do is ask a number of important questions regarding your health and potential thyroid problems. These questions include whether you have been exposed to nuclear radiation or received radiation treatments as a child or teenager.
What about Radiation Exposure?
Ionizing radiation has been known for a number of years to be associated with a small increased risk of developing thyroid cancer. The risk is very small and the amount of radiation exposure is usually quite high. There is typically a delay of 20 years or more between radiation exposure and the development of thyroid cancer.
Radiation was used occasionally between the 1920s and 1950s to treat certain neck infections, such as recurrent tonsillitis and certain skin conditions (such as severe acne).
In July 1997, the US government announced the results of a scientific study to determine if nuclear weapons testing in the southeast US from 1945 through the 1970s would have an effect on the development of thyroid cancer in Americans. This epidemiological study determined that these nuclear tests would likely increase the amount of thyroid cancers seen in Americans over the next several decades. The risks are substantially greater for those patients living nearby the test sites for many years. If there is any good news to this report, it is that these cancers will typically be of the well-differentiated type that have an excellent prognosis. The vast majority of these can be cured. There is no evidence that children are at increased risk of developing thyroid cancer; the small increase risk appears to be limited to those who were directly exposed in the past. Despite these increased risks, thyroid cancer is still relatively uncommon and usually very curable.