Treatment for thyroid cancer is tailored to each individual and may include surgery, radiation, and or systemic therapy with precision cancer medicines, immunotherapy or chemotherapy. The specific treatment depends on the type, stage and genomic profile of the cancer.
The standard initial treatment for all thyroid cancers typically includes surgical removal of the thyroid. Radioactive iodine (RAI) is often used in some patients with follicular or papillary cell-derived thyroid cancers. The majority of individuals with follicular or papillary cancer are cured by standard therapy, however a small fraction of follicular and papillary as well as many medullary and almost all anaplastic thyroid cancers are not cured and instead spread to distant metastatic sites.
If grouped together as “advanced thyroid cancers,” aggressive forms of thyroid cancer have a less than 50% 5-year survival rate in contrast to the ~ 98% 5-year survival for papillary and follicular types.1,2,3,4,5
Surgery: Patients with early stage thyroid cancer are curable with surgical removal of the cancer. Surgery to remove the entire thyroid is called a total thyroidectomy. Partial removal of the thyroid is called a lobectomy. The choice of procedure depends on age of the patient and the size of the cancer.
Patients who are at a high risk of cancer recurrence are treated with total thyroidectomy, however a total thyroidectomy is associated with a greater risk of side effects. A total thyroidectomy is a very specialized procedure and is best executed by a skilled surgeon who has performed this operation many times. The thyroid is in close proximity to the voice box and there is a risk of injuring the nerve and thus function of the voice box.1
In general surgeons who perform thyroid surgery more frequently have improved outcomes, fewer complications and shorter hospital stays. Surgeons who perform more than 25 thyroid removal surgeries per year have 55% fewer complications than those who perform less.11
Thyroid Hormone Replacement: Regardless of whether a patient has a lobectomy or has the entire thyroid gland removed, they will receive supplemental thyroid hormone for the rest of their lives. Thyroid hormone is produced by the thyroid gland and is critical for maintaining metabolism. Supplemental thyroid hormone (levothyroxine) serves two purposes: to maintain hormone levels in the absence of a functioning thyroid and to suppress further growth of the gland and thus the cancer. The pituitary gland located in the brain produces a hormone that stimulates the thyroid to grow—called thyroid-stimulating hormone (TSH). In the presence of thyroid hormone, TSH remains low and removes the stimuli to any remaining cancer cells.
Radioactive Iodine Treatment: Iodine is a natural substance that the thyroid uses to make thyroid hormone. The radioactive form of iodine is collected by the thyroid gland in the same way as non-radioactive iodine. Since the thyroid gland is the only area of the body that uses iodine, the radiation does not concentrate in any other areas of the body. The radioactive iodine that is not taken up by thyroid cells is eliminated from the body, primarily in urine. It is therefore a safe and effective way to test and treat thyroid conditions.
Research indicates that treatment with RAI improves survival for patients with thyroid cancer that has spread to nearby lymph nodes or to distant locations in the body.5 Anaplastic and medullary thyroid carcinoma are inherently non-sensitive to radioactive iodine treatment.
Radiation Therapy
External beam radiation therapy (EBRT) and Intensity-modulated radiation therapy (IMRT) can be used to treat certain patients with thyroid cancer. Conventional radiation therapy that is delivered with a machine that directs several high-energy beams at the area of the cancer is called EBRT.
IMRT allows radiation to be delivered more precisely with the use of the following advanced techniques:
- Three-dimensional scans of the cancer help determine where the radiation should be targeted.
- A rotating device delivers radiation from every point around the cancer, rather than only a few points as with conventional radiation therapy.
- Special blocking devices—called leaves—direct the radiation away from sensitive organs and toward the cancer.
IMRT appears to reduce the chance of injury to healthy body structures that are near the cancer while delivering higher doses of radiation to the cancer. In the treatment of thyroid cancer, this means that sensitive cells in the neck area—such as the cells that line the throat—may be spared from radiation damage, reducing side effects and improving quality of life.
Findings reported by researchers in New York suggest that IMRT is an effective treatment for select cases of thyroid cancer.4
Systemic Therapy: Precision Cancer Medicine, Chemotherapy, and Immunotherapy
Systemic therapy is any treatment directed at destroying cancer cells throughout the body. Some patients with early stage cancer already have small amounts of cancer that have spread outside the thyroid. These cancer cells cannot be treated with surgery alone and require systemic treatment to decrease the chance of cancer recurrence. Advanced stage and recurrent cancers and Anaplastic thyroid cancer that cannot be treated with surgery can only be treated with systemic therapy. Systemic therapies commonly used in the treatment of thyroid cancer include:
Chemotherapy
Chemotherapy is any treatment involving the use of drugs to kill cancer cells. Cancer chemotherapy may consist of single drugs or combinations of drugs, administered through a vein, or delivered orally in the form of a pill. Most chemotherapy drugs cannot tell the difference between a cancer cell and a healthy cell. Therefore, chemotherapy often affects the body’s normal tissues and organs, which can result in complications or side effects. In order to more specifically target the cancer and avoid unwanted side effects researchers are increasingly developing precision cancer medicines.
Precision Cancer Medicines
Through genomic-biomarker testing performed on the cancer or in blood doctors are increasingly able to define the genomic alterations in a cancers DNA that is driving the growth of a specific cancer. Once a genetic abnormality is identified, a specific targeted therapy can be designed to attack a specific mutation or other cancer-related change in the DNA programming of the cancer cells. Precision cancer medicine uses targeted drugs and immunotherapies engineered to directly attack the cancer cells with specific abnormalities, leaving normal cells largely unharmed. Precision medicines have been developed for the treatment of thyroid cancers with identifiable cancer driving mutations.6,7,8,9,10
Immuno-oncology
Precision immunotherapy treatment of cancer has also progressed considerably over the past few decades and has now become a standard treatment. The immune system is a network of cells, tissues, and biologic substances that defend the body against viruses, bacteria, and cancer. The immune system recognizes cancer cells as foreign and can eliminate them or keep them in check—up to a point. Cancer cells are very good at finding ways to avoid immune destruction, however, so the goal of immunotherapy is to help the immune system eliminate cancer cells by either activating the immune system directly or inhibiting the mechanisms of suppression of the cancer.
Researchers are mainly focused on two promising types of immunotherapy. One type creates a new, individualized treatment for each patient by removing some of the person’s immune cells, altering them genetically to kill cancer, and then infusing them back into the bloodstream the other uses precision medications to enhance the immune systems response to the cancer.
Treatment of Thyroid Cancer by Stage
Stage I-II: Stage I-II thyroid cancers are generally confined to the thyroid, but may include multiple sites of cancer within the thyroid.
Stage III: Stage III thyroid cancer is greater than 4 cm in diameter and is limited to the thyroid or may have minimal spread outside the thyroid. Stage III thyroid cancer is also referred to as locally advanced disease.
Stage IV: Stage IV thyroid cancer has spread beyond the thyroid to the soft tissues of the neck, lymph nodes in the neck, or distant locations in the body.
Recurrent: Thyroid cancer that has recurred after treatment or progressed with treatment is called recurrent disease.
References
1 Hadoux J, et al. Management of advanced medullary thyroid cancer. Lancet Diabetes Endocrinol. 2016;4(1):64–71. Doi: 10.1016/S2213-8587(15)00337-X.
2 Spitzweg C, et al. Advanced radioiodine-refractory differentiated thyroid cancer: the sodium iodide symporter and other emerging therapeutic targets. Lancet Diabetes Endocrinol. 2014;2(10):830–842. Doi: 10.1016/S2213-8587(14)70051-8.
3 Cabanillas ME, et al. Anaplastic thyroid carcinoma: treatment in the age of molecular targeted therapy. J Oncol Pract. 2016;12(6):511–518. Doi: 10.1200/JOP.2016.012013.
4 Rosa Pelizzo M, Toniato A, Boschin IM, et al. Locally advanced differentiated thyroid carcinoma: a 35-year mono-institutional experience in 280 patients. Nucl Med Commun. 2005;26(11):965-8.
5 Podnos YD, Smith D, Wagman LD, Ellenhorn JD. Radioactive iodine offers survival improvement in patients with follicular carcinoma of the thyroid. Surgery. 2005;128(6):1072-6.
6 Nikiforov YE. Thyroid carcinoma: molecular pathways and therapeutic targets. Mod Pathol. 2008;21(Suppl 2):S37–S43. Doi: 10.1038/modpathol.2008.10.
7 Agrawal N, et al. Integrated genomic characterization of papillary thyroid carcinoma. Cell. 2014;159(3):676–690. Doi: 10.1016/j.cell.2014.09.050
8 Cooper DS, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2009;19(11):1167–1214. Doi: 10.1089/thy.2009.0110.
9 Haugen BR, et al. 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer: the American Thyroid Association guidelines task force on thyroid nodules and differentiated thyroid cancer. Thyroid. 2016;26(1):1–133. Doi: 10.1089/thy.2015.0020.
10 https://news.cancerconnect.com/thyroid-cancer/therapies-show-initial-effectiveness-in-subset-of-papillary-thyroid-cancer-QD1zRQ5kokai-tqLitL3lA/
11 Adam MA, Thomas S, Youngwirth L, et al. Is there a minimum number of thyroidectomies a surgeon should perform to optimize patient outcomes? Annals of Surgery. 2017;265(2):402-7. Doi: 10.1097/SLA.0000000000001688.