What Is Thyroid Cancer?

Learn the symptoms, diagnosis and treatments

A woman feels her neck area for signs of thyroid problems.

Learn the symptoms, diagnosis and treatments

Thyroid cancer is the most common type of endocrine cancer in the United States. About 44,000 new cases will be diagnosed this year, according to the American Cancer Society. About 75% of cases occur in women.

Thyroid cancer is highly treatable especially if caught early or before it can spread to other parts of the body. In addition, thyroid cancers are being detected earlier due to improved testing, which has led to more successful treatment outcomes.

“Thyroid cancer has a good prognosis when caught and treated early,” says Christopher Marx, MD, an endocrinologist at Scripps Clinic. “Most cases respond well to treatment, which is why it’s important to know the signs and symptoms and your risk factors, especially if thyroid cancer runs in your family.”

What is thyroid cancer?

Thyroid cancer happens when cancer cells grow abnormally in the thyroid gland, which is in the front part of the neck. The gland produces hormones that regulate metabolism, heart rate, blood pressure and body temperature. If cancer develops in the thyroid gland, it can disrupt these functions.

Thyroid cancer and thyroid disease are related to the thyroid gland, but they are not the same.

Thyroid disease, a condition that keeps the gland from making the right amount of hormones, is much more prevalent, impacting millions of Americans. Thyroid cancer, while less common, is still a significant concern. More than 2,000 related deaths are expected this year.

There are several types of thyroid cancers. Papillary and follicular thyroid cancers are the most common.

Who is at risk?

While anyone can develop thyroid cancer, certain factors can increase the risk, including age, sex and family history.

“You can get thyroid cancer at any age,” says Brendan Gaylis, MD, an otolaryngologist at Scripps Cancer Center and Scripps Clinic. However, it is often found in younger people, usually around age 51 on average.

Women also are three times more likely than men to develop the disease. Experts believe this could be linked to the hormone estrogen.

Other risk factors include:

  • Genetic conditions like familial medullary thyroid cancer
  • Childhood or adolescent radiation exposure, including from certain medical treatments
  • Excess weight or obesity

“Having risk factors does not mean you will definitely get cancer but if you have any concerns or symptoms, see your doctor,” Dr. Gaylis says.

Thyroid cancer symptoms

In its earliest stages, thyroid cancer may not show any signs or symptoms.


“Most thyroid cancers are found by accident,” says Dr. Marx. “Someone may feel a lump in their own neck, but more often, someone else points it out to them — a friend or family member, or even a hairdresser or dentist. They will notice a difference in symmetry — a fullness in one side of the neck but not the other — but it’s painless.”


Other signs include:

  • An increasingly hoarse voice 
  • Difficulty swallowing
  • Neck or throat pain
  • Swollen lymph nodes in the neck

Lumps or bumps in the thyroid gland are called thyroid nodules. Most are benign, but about 2 or 3 out of 20 are cancerous.

Some thyroid nodules can be left alone if they are not growing or causing symptoms. Others may need treatment.


Patients with symptoms may be referred to an endocrinologist for testing, which may include: 

  • Blood tests to check thyroid hormone levels
  • Imaging tests, including ultrasound, to look for tumors or see if the cancer has spread beyond the thyroid gland
  • Biopsy, or removal of small amounts of thyroid tissue for close examination


Treatment for thyroid cancer depends on the type and stage of the disease. It also depends on the patient's overall health and preferences. Often, more than one type of treatment is needed.

Surgery is often the first line of treatment. The extent of the surgery depends on the size and location of the tumor.

Radioactive iodine therapy is often used after surgery to destroy any remaining cancer cells. Patients must isolate for a few days to prevent others from being exposed to radiation.

Thyroid hormone therapy is used to replace the hormones that the thyroid gland would normally produce.

Sometimes, different treatments are needed. Radiation therapy uses beams to kill cancer cells. Chemotherapy uses drugs to kill cancer cells throughout the body. These treatments are common when the cancer has spread beyond the thyroid gland.

Regular check-ups are important for patients as the cancer can come back even years after treatment. 

Promising treatments

Dr. Marx is optimistic about the future of treatment for thyroid cancer. 

“While the detection rate for thyroid cancer now is quite high, the death rate remains minimal,” he says. “As with many diseases, the science has gotten better. Genetic testing has eliminated some unnecessary surgery, and the prognosis for most people remains very good.”

Scripps offers advanced thyroid cancer diagnosis and treatment services, including single-site robotic surgery and the newest radiation therapy technologies.

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