Farmin Shahabuddin, MPH and Akashleena Mallick, MD, MPH, Cancer Prevention and Treatment Fund
A Small Gland with a Big Job
Your thyroid is a small, butterfly-shaped gland at the front of your neck. If you have a noticeable Adam’s apple, it is just below that. Your thyroid makes hormones that help control your metabolism, heart rate, blood pressure, and body temperature. Thyroid cancer happens when cells in this gland begin to grow out of control. Sometimes these cells form a lump called a nodule, but most nodules are not cancerous, and not every thyroid cancer shows up as a nodule. In fact, only about 5% of thyroid nodules are cancerous. Many early thyroid cancers cause no symptoms and are found by chance, when a doctor feels a lump during a routine checkup or notices something on imaging that was done for another reason.
Thyroid cancer can develop at any age, though it is usually found in adults. Fortunately, it is less dangerous than other cancers, and about 98% of people diagnosed with thyroid cancer are alive 5 years later.1 Survival rates vary by the type and stage of the cancer, but the outlook is very good for most patients.
The Four Main Types
It’s important to know that the different types of thyroid cancer behave differently:
- Papillary thyroid cancer is by far the most common — about 80% of patients. It usually grows slowly and responds very well to treatment.2
- Follicular thyroid cancer accounts for about 10% of cases. It also tends to grow slowly, but it can sometimes spread to the lungs or bones.2
- Medullary thyroid cancer is only about 4% of patients, and it can run in families through a gene change called RET.3
- Anaplastic thyroid cancer is only about 2% of cases and is the most aggressive and fastest growing.2
Radiation and Thyroid Cancer
One known cause of thyroid cancer is exposure to radiation, especially during childhood and adolescence, when the thyroid gland is most sensitive.4 The main causes are radiation therapy to the head or neck and radiation from nuclear accidents. The good news is that most medical imaging is not a major concern, since tests like dental X-rays expose the thyroid to very small amounts of radiation. However, repeated higher-dose scans, such as CT scans of the head, neck, or chest done many times over the years, can cause thyroid cancer.4 For a closer look at how different types of radiation can affect the thyroid, see our article on Radiation and Thyroid Cancer.
Why Thyroid Cancer Is Often Overdiagnosed
Overdiagnosis in thyroid cancer occurs when very small, slow-growing tumors are correctly diagnosed as cancer but are so unlikely to grow or spread that they would never have caused symptoms, harmed a person’s health, or shortened their life if they are not treated.5 This is not a wrong diagnosis, which would be if someone is told they have cancer when they actually do not. However, not all thyroid cancers grow slowly, so any thyroid nodule or cancer diagnosis needs to be carefully evaluated by a doctor.
About 44,000 people in the United States are expected to be diagnosed with thyroid cancer every year, and about 2,300 people will die from it each year. Diagnoses have increased over the past few decades, yet the number of people dying from thyroid cancer has remained relatively stable.6 About 75% of people diagnosed with thyroid cancer are women, particularly with small papillary thyroid cancer (2 cm or less).7 One reason for this sex difference is that women use health care more often than men, increasing the chances that thyroid nodules will be found.6 Biological reasons for the difference are still being studied.6 Men may be diagnosed later because thyroid cancer is lower on the list of conditions doctors think to check for in men.6
Higher dose imaging tests, such as CT scans of the head, neck, or chest, and repeated radiation exposure over time, have also resulted in an increase in thyroid cancer diagnoses.8 These scans can spot tiny nodules that doctors may not be able to feel during a physical exam. Many scans are ordered for completely unrelated reasons, such as neck pain, dental problems, car accident injuries, or checkups for heart and lung conditions, so small thyroid nodules can be found accidentally. Once a nodule is seen on a scan, it usually leads to more tests, such as a biopsy, and sometimes to surgery. This happens because doctors cannot always predict which nodules will become dangerous and which ones never will, so they often choose to treat it just to be safe.8
Signs to Watch For
Many thyroid cancers cause no symptoms at all, especially in the early stages. When symptoms do appear, they can include a lump or swelling in the neck, hoarseness or other voice changes, trouble swallowing, pain in the front of the neck, or a cough that does not go away.9 However, these same symptoms are rarely caused by cancer, and instead due to a cold or a benign nodule, but if any of them last more than a couple of weeks, it is a good idea to go to your doctor to check.
How Thyroid Cancer Is Treated
Treatment depends on the type and stage of the cancer, as well as the person’s age and overall health.10 For a long time, surgery to remove part or all of the thyroid gland was the standard treatment for almost everyone.¹¹ That is now changing. For people with very small, slow-growing papillary cancers, many doctors now recommend active surveillance instead. This means the cancer is carefully watched with regular ultrasounds, and treatment is started only if it begins to grow or change.14 Studies have shown that many of these small cancers grow very slowly, if at all, so surgery can often be safely delayed or avoided altogether.14
Surgery is usually recommended for larger tumors, cancers that have spread beyond the thyroid, or the more aggressive types, such as medullary or anaplastic thyroid cancer.10 When surgery is needed, it can cause harm. The nerves that control the vocal cords can sometimes be bruised or injured, leading to a weaker voice or, in rare cases, trouble breathing.¹¹ The parathyroid glands, four tiny glands on the back of the thyroid that control calcium levels, can also be accidentally damaged, leaving some people with muscle cramps or tingling in the hands and feet. When these glands are injured, the body can no longer keep calcium at a healthy level on its own, so some people will need to take calcium and vitamin D pills for the rest of their lives.¹¹ People who have their whole thyroid removed also need a daily hormone replacement pill for the rest of their lives, and determining the right dose can take months or even years.¹³ Too low a dose can cause tiredness, weight gain, and trouble concentrating, while too high a dose can cause a fast heartbeat, anxiety, trouble sleeping, and weaker bones over time.¹³
Surgery is not always the only treatment. Some patients also receive radioactive iodine therapy, which uses radioactive iodine to destroy any leftover thyroid cells, and this can cause side effects such as dry mouth, changes in taste, and a temporary drop in the body’s ability to fight infection.¹² For advanced or aggressive cancers, doctors may also recommend external beam radiation, targeted drug therapy, or, in rare cases, chemotherapy.15 On top of the physical effects, many survivors report lasting fatigue, anxiety, depression, and a sense of uncertainty about the future, even years after treatment ends.16
Some physicians still tend to recommend surgery even when active surveillance would be a reasonable option, often because they or their patients feel more at ease knowing the cancer has been removed.17 But peace of mind can come at a real cost when the treatment itself causes harm that the cancer never would have. That is why many thyroid cancer specialists now encourage a more cautious, individualized approach for small, slow-growing tumors.
Questions Worth Asking Your Doctor
If you or a loved one has been diagnosed with thyroid cancer, it is a good idea to come to appointments prepared. We agree with the American Cancer Society’s recommended questions:18
- Is my cancer the slow-growing kind, or is it more aggressive?
- Do I need treatment right away, or could active surveillance be an option for me?
- What are the risks and benefits of treating this cancer now versus monitoring it?
- What are the possible short-term and long-term effects of each treatment?
- How will treatment affect my daily life, my voice, and my energy? And what does recovery usually look like?
The Bottom Line
Thyroid cancer is common and is rarely life-threatening, so most patients do not need surgery. For many people, especially those with small, slow-growing papillary cancers, careful monitoring may enable you to live just as long as you would with surgery while avoiding the side effects described above. The best decisions come from honest conversations between patients, families, and doctors, based on the most up-to-date evidence and guided by what matters most to you.
References
- National Cancer Institute. (2024). SEER cancer stat facts: Thyroid cancer. Surveillance, Epidemiology, and End Results Program. https://seer.cancer.gov/statfacts/html/thyro.html
- American Cancer Society. (2024). Survival rates for thyroid cancer. https://www.cancer.org/cancer/types/thyroid-cancer/detection-diagnosis-staging/survival-rates.html
- Mathiesen, J. S., Effraimidis, G., Rossing, M., Rasmussen, Å. K., Hoejberg, L., Bastholt, L., Godballe, C., Oturai, P., & Feldt-Rasmussen, U. (2023). Multiple endocrine neoplasia type 2 and medullary thyroid carcinoma. The Journal of Clinical Endocrinology & Metabolism, 108(2), 271–282. https://academic.oup.com/jcem/article/108/2/271/6795262
- Smith-Bindman, R., Chu, P. W., Azman Firdaus, H., Stewart, C., Malekhedayat, M., Alber, S., Bolch, W. E., Mahendra, M., Berrington de González, A., & Miglioretti, D. L. (2025). Projected lifetime cancer risks from current computed tomography imaging. JAMA Internal Medicine, 185(6), 710–719. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2832778
- Papaleontiou, M., & Haymart, M. R. (2020). Too much of a good thing? A cautionary tale of thyroid cancer overdiagnosis and overtreatment. Thyroid, 30(5), 651–652. https://doi.org/10.1089/thy.2020.0080
- LeClair, K., Bell, K. J. L., Furuya-Kanamori, L., Doi, S. A., Francis, D. O., & Davies, L. (2021). Evaluation of gender inequity in thyroid cancer diagnosis: Differences by sex in US thyroid cancer incidence compared with a meta-analysis of subclinical thyroid cancer rates at autopsy. JAMA Internal Medicine, 181(10), 1351–1358. https://doi.org/10.1001/jamainternmed.2021.4804
- Chen, D. W., Lang, B. H. H., McLeod, D. S. A., Newbold, K., & Haymart, M. R. (2023). Thyroid cancer. The Lancet, 401(10387), 1531–1544. https://doi.org/10.1016/S0140-6736(23)00020-X
- Li, M., Dal Maso, L., Pizzato, M., & Vaccarella, S. (2024). Evolving epidemiological patterns of thyroid cancer and estimates of overdiagnosis in 2013–2017 in selected countries. JAMA Network Open, 7(8), e2429045. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2845450
- American Cancer Society. (2024). Signs and symptoms of thyroid cancer. https://www.cancer.org/cancer/types/thyroid-cancer/detection-diagnosis-staging/signs-symptoms.html
- American Cancer Society. (2024). Treatment of thyroid cancer, by type and stage. https://www.cancer.org/cancer/types/thyroid-cancer/treating/by-stage.html
- American Cancer Society. (2024). Surgery for thyroid cancer. https://www.cancer.org/cancer/types/thyroid-cancer/treating/surgery.html
- American Cancer Society. (2024). Radioactive iodine (radioiodine) therapy for thyroid cancer. https://www.cancer.org/cancer/types/thyroid-cancer/treating/radioactive-iodine.html
- American Cancer Society. (2024). Thyroid hormone therapy. https://www.cancer.org/cancer/types/thyroid-cancer/treating/thyroid-hormone-therapy.html
- Tuttle, R. M., Fagin, J. A., Minkowitz, G., Wong, R. J., Roman, B., Patel, S., Untch, B., Ganly, I., Shaha, A. R., Shah, J. P., Pace, M., Li, D., Bach, A., Lin, O., Whiting, A., Ghossein, R., Landa, I., Sabra, M., Boucai, L., … Sherman, E. (2022). Active surveillance of papillary thyroid cancer: Frequency and time course of the six most common tumor volume kinetic patterns. JAMA Oncology, 8(11), 1588–1596. https://jamanetwork.com/journals/jamaoncology/fullarticle/2796440
- American Cancer Society. (2024). Targeted drug therapy for thyroid cancer. https://www.cancer.org/cancer/types/thyroid-cancer/treating/targeted-therapy.html
- Applewhite, M. K., James, B. C., Kaplan, S. P., Angelos, P., Kaplan, E. L., Grogan, R. H., & Aschebrook-Kilfoy, B. (2016). Quality of life in thyroid cancer survivors: A systematic review. Thyroid, 26(11), 1533–1541. https://journals.sagepub.com/doi/10.1089/thy.2015.0098
- Haymart, M. R., Miller, D. C., & Hawley, S. T. (2021). Physician perspectives on the treatment of low-risk thyroid cancer. JAMA Network Open, 4(12), e2140841. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2791285
- American Cancer Society. (2024). Questions to ask your doctor about thyroid cancer. https://www.cancer.org/cancer/types/thyroid-cancer/detection-diagnosis-staging/talking-with-doctor.html

