The short answer
Thyroid cancer is a disease in which cancer cells form in the tissues of the thyroid gland, a butterfly-shaped gland at the base of the throat. It can be described as differentiated thyroid cancer (which includes papillary, follicular, and anaplastic) or medullary thyroid cancer. Thyroid cancer found at an early stage can often be treated successfully.
Thyroid cancer forms in the tissues of the thyroid gland, at the base of the throat near the windpipe.
The thyroid makes hormones that control heart rate, body temperature, metabolism, and the amount of calcium in the blood.
Thyroid cancer is described as differentiated (papillary, follicular, and anaplastic) or medullary.
The types differ in how aggressive they are; well-differentiated tumors can usually be cured.
Subjective: What you might experience
This section describes the symptoms and history a patient might report to their doctor.
A lump or swelling in the front of the neck.
Hoarseness or voice changes that don't go away.
Trouble swallowing or breathing.
Neck or throat discomfort, or swollen neck lymph nodes.
Often found incidentally on imaging or a routine exam with no symptoms.
Risk history
radiation exposure to the head/neck, family history, and certain inherited syndromes.
Objective: Tests and findings
Neck exam of the thyroid and lymph nodes.
Thyroid ultrasound to characterize nodules.
Fine-needle aspiration biopsy of suspicious nodules
the key diagnostic test.
Thyroid function tests (TSH) and, for medullary type, calcitonin.
Additional imaging or radioiodine scans when needed.
Interactive anatomy guide
Explore where cancers start and how they are found, on an interactive body map.
Open the anatomy guideAssessment: Staging and prognosis
Types include papillary, follicular, medullary, and anaplastic
with very different behavior.
Diagnosis confirmed by biopsy or surgical pathology.
Staged with the TNM system, with age factored in for the common differentiated types.
Most differentiated thyroid cancers have an excellent prognosis.
Plan: The treatment approach
Surgery to remove part or all of the thyroid, sometimes with lymph nodes.
Radioactive iodine therapy for certain differentiated cancers after surgery.
Thyroid hormone therapy to replace hormone and suppress recurrence.
Targeted therapy for advanced or specific types; clinical trials.
Monitoring with thyroglobulin, TSH, and neck ultrasound.
These are simplified, educational SOAP-style summaries showing the kinds of findings clinicians document when evaluating each cancer, based on National Cancer Institute resources. They describe typical diagnostic criteria and workups — not a real patient, and not medical advice. Real clinical notes are individualized. Always rely on your own care team. Based on National Cancer Institute educational content. Educational only — not medical advice.
Words to know
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Common questions
Where does thyroid cancer start?
Thyroid cancer forms in the tissues of the thyroid gland. The thyroid is a gland at the base of the throat near the trachea (windpipe). It is shaped like a butterfly, with a right lobe and a left lobe connected by a thin piece of tissue called the isthmus.
What does the thyroid do?
The thyroid uses iodine to help make several hormones. These thyroid hormones control heart rate, body temperature, and how quickly food is changed into energy (metabolism). They also help control the amount of calcium in the blood.
What are the main types of thyroid cancer?
Thyroid cancer can be described as differentiated thyroid cancer or medullary thyroid cancer. Differentiated thyroid cancer includes well-differentiated tumors (papillary and follicular thyroid cancer), poorly differentiated tumors, and undifferentiated tumors (anaplastic thyroid cancer). The types differ in how aggressive they are. Well-differentiated tumors can usually be cured, while anaplastic tumors grow and spread quickly.
Are thyroid nodules cancer?
Thyroid nodules are common but usually are not cancer. A nodule is an abnormal growth of thyroid cells that may be solid or fluid-filled. Only a small number of thyroid nodules are diagnosed as cancer. When a nodule is found, tests such as an ultrasound and a fine-needle biopsy may be used to check for signs of cancer.
What can affect the risk of thyroid cancer?
Age, sex, and being exposed to radiation can affect the risk of thyroid cancer. Some medullary thyroid cancer is caused by a gene change passed from parent to child. Your healthcare team can explain risk factors that may apply to you.
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Sources last checked: 2026-07-21 what this meansLast updated: 2026-07-21Next 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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