The short answer
Most thyroid cancers are differentiated types — papillary and follicular — which grow slowly and are highly treatable. Less common types include medullary and anaplastic thyroid cancer. The type strongly affects treatment and outlook.
Most thyroid cancers are papillary or follicular, which are highly treatable.
Papillary thyroid cancer is the most common type and usually grows slowly.
Medullary thyroid cancer is less common and can run in families.
Anaplastic thyroid cancer is rare but fast-growing.
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The full explanation.
Why type matters more than "thyroid cancer" alone
The thyroid is a small gland in the neck. It makes hormones that control your metabolism. "Thyroid cancer" covers four quite different diseases. They range from one of the most treatable cancers there is to one of the hardest to treat. Knowing which type you have changes almost everything about what to expect.
Papillary thyroid cancer: the most common, and the most treatable
About 8 in 10 thyroid cancers are papillary thyroid cancer. It usually grows very slowly. It often stays in just one part of one lobe of the thyroid. It can sometimes spread to lymph nodes in the neck. Even then, outcomes are excellent. This is the type most people picture when they hear a reassuring thyroid cancer diagnosis. There is good reason for that. With proper treatment, most people do very well.
Follicular thyroid cancer: less common, still generally treatable
Follicular thyroid cancer makes up about 1 in 10 thyroid cancers, making it the second most common type. It behaves a bit differently than papillary cancer. It rarely spreads to nearby lymph nodes. It can spread farther, though, to the lungs or bones through the bloodstream. Despite that difference, the overall outlook remains favorable for most people. It is only slightly less favorable than papillary cancer.
Medullary thyroid cancer: sometimes inherited
Medullary thyroid cancer, or MTC, makes up less than 5% of thyroid cancers. It starts in a different cell type than papillary or follicular cancer. These cells make a hormone called calcitonin, unlike most of the hormone-producing cells in the thyroid. MTC can be harder to find and treat. It can spread to lymph nodes, lungs, or the liver before it is caught.
About a quarter of MTC cases are inherited. They pass down through families as part of a genetic syndrome. That syndrome also raises the risk of other tumors. If you are diagnosed with MTC, genetic testing is usually recommended. This applies to you and, if a mutation is found, to your close relatives too. Finding it early in a family member can mean treating, or even preventing, their thyroid cancer before it starts.
Anaplastic thyroid cancer: rare and aggressive
Anaplastic thyroid cancer makes up only about 2% of thyroid cancers, but it behaves nothing like the others. It often spreads quickly into the neck and to distant parts of the body. It can be hard to treat. Doctors believe it sometimes develops from an existing papillary or follicular cancer. That cancer transforms into this more aggressive form, rather than starting this way from the beginning. Because it moves fast, anaplastic thyroid cancer is treated urgently. Treatment often combines surgery, radiation, and drug therapy, started as quickly as possible after diagnosis.
Why the type-outlook gap is so wide here
Thyroid cancer has an unusual range. Some types are so treatable that people are told not to worry much. Others are treated as a true emergency. That range is exactly why "I have thyroid cancer" does not tell you much on its own. The specific type on your pathology report is one of the most important pieces of information you can have.
What to ask your team
- Which specific type of thyroid cancer do I have?
- Given my type, what is the expected course of treatment and outlook?
- If I have medullary thyroid cancer, should I have genetic testing, and should my relatives be tested too?
- How urgently does my type need to be treated?
Sources
Words to know
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Common questions
What are the main types?
Most thyroid cancers are 'differentiated' types — papillary (the most common) and follicular — which grow slowly and are highly treatable. Less common types are medullary and anaplastic thyroid cancer.
What is medullary thyroid cancer?
It is a less common type that starts in different thyroid cells and can sometimes run in families. People with it may be offered genetic testing.
What is anaplastic thyroid cancer?
It is a rare, fast-growing type that is more difficult to treat than the common differentiated types. It is much less common.
Why does the type matter?
The type strongly affects treatment and the outlook. The common papillary and follicular types usually have an excellent outlook, especially when found early.
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Sources last checked: 2026-07-21 what this meansLast updated: 2026-08-05Next planned review: 2027-07-21
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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