About the Thyroid Gland
What is the thyroid gland and what does it do?
The purpose of your thyroid gland is to make, store, and release thyroid hormones into your blood (provide link to “About the Thyroid Gland” document that we already approved for upload).. These hormones, which are also referred to as T3 (liothyronine) and T4 (levothyroxine), affect almost every cell in your body, and help control your body’s functions. If you have too little thyroid hormone in your blood, your body slows down. This condition is called hypothyroidism. If you have too much thyroid hormone in your blood, your body speeds up. This condition is called hyperthyroidism
What causes Thyroid cancer?
Usually, we don’t know the specific cause of an individual patient’s thyroid cancer. The majority of thyroid cancer has no apparent cause, and thyroid cancer can occur in anyone… Thyroid cancer is also more likely to occur if you have a family member who has had thyroid cancer. Radiation that is used in diagnostic x-rays (for example, x-rays used by dentists or CT scans of the neck/chest) is probably not connected with thyroid cancer, For example, large epidemiologic series of patients in whom radioactive iodine was used for thyroid function testing have not been associated with increased cancer risk. However, thyroid cancer is more likely to occur in people who have undergone radiation therapy of the head, neck, or chest during childhood. Radiation was commonly used before 1960 to shrink enlarged tonsils or adenoids, to treat various skin problems (such as acne), and to reduce an enlarged thymus gland (an organ inside the chest) in infants. Radiation exposure following the Chernobyl nuclear power plant reactor tragedy resulted in more than 5,000 cases of thyroid cancer in children exposed to the fallout in April 1986.
Types of Thyroid Cancer
There are four main types of thyroid cancer: (1) Papillary thyroid cancer, (2) Follicular thyroid cancer, (3) medullary thyroid cancer, and (4) anaplastic thyroid cancer. Papillary thyroid cancer is the most common type and represents more than 90% of all thyroid cancers. There are multiple subtypes of papillary thyroid cancer that may have a better or worse prognosis than classical forms of papillary thyroid cancer. While the prognosis and follow-up of these various subtypes may vary slightly depending on the variant, overall the treatment and management of these tumors is similar. Papillary, follicular and anaplastic thyroid cancer all arise from the normal thyroid follicular cell which makes thyroid hormone. Medullary thyroid cancers are different in that they arise from other neuroendocrine cells that live within the thyroid.
What is different about medullary thyroid cancer?
Except for medullary thyroid cancer, the other common types of other thyroid cancers arise from a thyroid follicular cell (the normal thyroid cell that concentrates iodine and produces/stores/releases thyroid hormone). Medullary thyroid cancer arises from a different cell type within the thyroid gland (c-cells). These c-cells are neuroendocrine cells that are very different from thyroid follicular cells in that they do not concentrate iodine and they do not make thyroid hormones.
Unlike the other thyroid cancers, medullary thyroid cancer may be part of a hereditary syndrome in which each first degree relative of an affected patient has a 50% chance of developing medullary thyroid cancer. The genetic mutation for hereditary thyroid cancer is now well known and its detection is possible with a commercially available blood test (RET proto-oncogene). Of all the patients with medullary thyroid cancer, only 25% have a genetic syndrome that can be passed through a family. The other 75% have sporadic medullary thyroid cancer that affects only that patient and is not hereditary.
Unlike papillary and follicular thyroid cancers with make thyroglobulin, medullary thyroid cancer makes tumors markers known as calcitonin and CEA (carcinoembryonic antigen). In addition, the cells that give rise to medullary thyroid cancer are not sensitive to TSH, so thyroid hormone suppressive therapy is not needed. Rather, in medullary thyroid cancer the thyroid hormone levels are adjusted to achieve a TSH in the normal reference range.
Is thyroid cancer hereditary?
As a general rule, the common forms of thyroid cancer (papillary and follicular) are not thought to be hereditary. However, some studies do suggest that perhaps as many as 3-4% of patients with thyroid cancer have more than 2 first degree relatives with thyroid cancer suggesting that it can occasionally be hereditary within a family. As of now, there is no specific genetic test that can be used to look for hereditary thyroid cancer of the papillary and follicular types.
For papillary and follicular thyroid cancer, we do not routinely recommend special screening or additional testing of family members beyond routine thyroid blood tests and a physical examination of the thyroid.
Medullary thyroid cancer can be hereditary in as many as 25% of patients diagnosed. The genetic cause is well known and can be evaluated using a commercially available blood test (RET proto-oncogene).
What is different about thyroid cancer in teenagers?
When thyroid cancer is diagnosed in teenagers, it is almost always papillary thyroid cancer. For reasons that are not clear, teenagers and children with thyroid cancer often have lots of neck lymph nodes involved with the thyroid cancer and some even have thyroid cancer spread to the lungs. However, teenagers with thyroid cancer have an excellent overall prognosis and are usually expected to live full productive lives. While recurrence rates are high, the recurrences are usually very treatable with additional surgery and/or radioactive iodine therapy and therefore are not associated with any significant change in overall survival.
What is multidisciplinary management?
The treatment of thyroid cancer is often a cooperative effort requiring several different specialists including endocrinologist, nuclear medicine expert, medical and radiation oncologist in addition to the primary care physician and surgeon. Treatment must be individualized at multiple points along the patient’s course, depending upon the nature and extent of the tumor, while not excluding factors of the patient’s general health, both physical and psychological, age and wishes. The complex management of the more aggressive tumor may require several different treatment modalities to provide the patient the best chance of cure with the best quality of life. The importance of one physician who is knowledgeable and sophisticated in the management of thyroid cancer to act as the captain of the ship, directing the treatment and enlisting the aid of other disciplines when and if necessary, cannot be overemphasized. Most, but not all, patients will do well if the disease is detected early and managed appropriately and carefully.
How can I get back on with my life?
It is scary to find out you have thyroid cancer. But after you finish your initial treatments and you are taking thyroid hormone therapy, your life can just about return to normal. Take good care of yourself by eating well, exercising regularly, and managing stress. Learning relaxation methods, learning to set priorities, and remembering to laugh all help to reduce stress. Take pleasure in doing things that you did before your diagnosis. Most of all make sure to get regular follow-up evaluations with your clinician -timing will vary depending on your risk of recurrence and your response to initial therapy. If you find it difficult to have regular checkups for any reason, talk with your doctor or nurse about your concerns.
Remember, you do not have to go through this alone. Talk to family and friends about whatever fears and questions you may have, and consider joining a thyroid cancer support group. At a support group, you will find other people who are willing to share their firsthand experience with thyroid cancer. To find a support group in your area, ask your doctor or nurse, or contact one of the thyroid cancer organizations listed in our links page.
What is new in the ATA 2016 guidelines for thyroid nodules and thyroid cancer?
In 2016, the American Thyroid Association published revised guidelines for the management of thyroid nodules and thyroid cancer. Overall, about 80% of the recommendations remain unchanged from previous editions. Most of the new changes related to their attempts to tailor the recommendations more specifically to the risk of recurrence and death from thyroid cancer for each individual patient. Both using risk estimates at the time of diagnosis but also describing ways to modify those initial risk estimates over time (risk adapted management).
With regard to nodules, the guidelines provided more guidance as to which nodules could be observed and which ones needed to be biopsied based on both the size of the nodule but also the other ultrasonographic features of the nodule.
The guidelines also provided at least 2 other conservative management options for low risk thyroid cancer which included (1) the option of observation rather than immediate surgery for very low risk thyroid cancers confined to the thyroid, and (2) the option of removing only half of the thyroid for selected patients with tumors less than 4 cm that appeared to be confined to the thyroid. Obviously, these conservative management options are not suitable or acceptable for all patients. Therefore, a discussion of the risks and benefits of the specific approach for an individual patient’s case is mandatory.
With the FDA approval of two new medications for the treatment of radioactive iodine refractory thyroid cancer (sorafenib, and lenvatinib), the 2016 guidelines provided much additional information regarding the use of these types of drugs, proper patient selection, and side effect management.