Conditions: Papillary Thyroid Carcinoma

Thyroid nodule versus thyroid cancer

A thyroid nodule is a general term for a growth or lump that forms within the thyroid gland. As about 5% of all nodules are cancerous, almost all thyroid nodules prove not to be cancerous after evaluation.

WHAT IS Papillary thyroid carcinoma?

Papillary thyroid carcinoma (PTC) is a type of cancer that starts in the thyroid gland — a small,butterfly-shaped gland at the front of your neck. The thyroid makes hormones that help controlyour metabolism, heart rate, and body temperature.

PTC is the most common type of thyroid cancer, making up about 85% of all thyroid cancers. It isclassified as a "well-differentiated" cancer, which means the cancer cells still look and behavesomewhat like normal thyroid cells. This is one of the reasons PTC tends to grow slowly andresponds well to treatment.

How common is it?

Thyroid cancer is the ninth most common cancer worldwide and the most common cancer inadolescents and young adults. In the United States, approximately 1.2% of people will bediagnosed with thyroid cancer at some point in their lifetime, and roughly 44,000 new cases arediagnosed each year — the vast majority of which are PTC.

PTC is about 3 to 4 times more common in women than in men. The median age at diagnosis is inthe early 50s, although it can occur at any age.

PTC is about 3 to 4 times more common in women than in men. The median age at diagnosis is in the early 50s, although it can occur at any age.

What causes it?

In most cases, the exact cause of PTC is not known. More than 90% of thyroid cancers arise from random genetic changes in the cells, without a clear trigger. However, several factors may increase the risk:

• Radiation exposure: Exposure to radiation during childhood — such as radiation therapy to the head and neck or exposure to nuclear fallout — is the strongest known risk factor.

• Family history: A small percentage of cases (about 3%–9%) run in families. Certain inherited conditions, such as familial adenomatous polyposis (FAP) and Cowden syndrome, are also associated with a higher risk.

• Sex and age: Women are more likely to develop PTC than men, and risk increases with age.

• Obesity: Being significantly overweight has been linked to a higher risk of PTC.

PTC is not caused by anything you did or didn't do. Most people who develop it have no identifiable risk factors.

What are the symptoms?

Most cases of PTC cause no symptoms at all, especially in the early stages. Many thyroid cancers are found incidentally — meaning they are discovered during imaging tests (such as an ultrasound or CT scan) done for an unrelated reason, or during a routine physical exam.

When symptoms do occur, they may include:

• A lump or nodule in the front of the neck that you or your doctor can feel

• Swollen lymph nodes in the neck

• Difficulty swallowing or a sensation of something pressing on your throat

• Hoarseness or voice changes (less common)

• Rarely, pain in the neck or throat

Having a thyroid nodule is very common and does not necessarily mean you have cancer. Most thyroid nodules are benign (not cancerous).

How is it diagnosed?

If a thyroid nodule is found, your doctor will use several steps to determine whether it is cancerous:

• Thyroid and neck ultrasound: This is the first and most important imaging test. It evaluates the size, shape, and characteristics of the nodule and checks for any enlarged lymph nodes in the neck. Certain features on ultrasound — such as irregular borders, tiny calcium deposits (microcalcifications), and a shape that is taller than it is wide — raise suspicion for cancer.

• Fine-needle aspiration (FNA) biopsy: A thin needle is used to take a small sample of cells from the thyroid nodule. This is the most reliable test to determine if a nodule is cancerous. It is a quick, minimally invasive procedure usually done in the doctor's office with ultrasound guidance.

• Additional imaging: In some cases, a CT scan or MRI of the neck may be done, particularly if there are suspicious lymph nodes or concern about the cancer extending beyond the thyroid.

• Blood tests: Thyroid function tests (such as TSH) are typically checked. These are usually normal in PTC but help guide overall management.

How is it treated?

Treatment depends on the size of the tumor, whether it has spread, and your individual risk factors. Your care team will work with you to develop a personalized treatment plan.

• Active surveillance (close monitoring): For very small cancers (1 cm or less) that are confined to the thyroid and do not have worrisome features, your doctor may recommend careful monitoring with regular ultrasounds instead of immediate surgery. Research has shown that most of these tiny cancers grow very slowly, and outcomes are just as good when surgery is delayed until needed. This approach is called "active surveillance" and involves ultrasounds every 6 months for the first 1–2 years, then annually.

• Thyroid surgery: Most PTC is treated with surgery. Depending on the size and extent of the cancer, this may involve:

  • Lobectomy: Removing the half of the thyroid that contains the cancer. This is often preferred for smaller tumors (1–4 cm) without high-risk features.

  • Total thyroidectomy: Removing the entire thyroid gland. This is recommended for larger tumors (over 4 cm), cancers that have spread to lymph nodes, or cancers with other high-risk features.

  • If cancer has spread to nearby lymph nodes, those nodes will be removed during surgery as well.

• Radioactive iodine (RAI) therapy: After total thyroidectomy, some patients receive radioactive iodine treatment to destroy any remaining thyroid tissue or cancer cells. This is more commonly used for larger tumors, cancers that have spread, or those with a higher risk of coming back. It is taken as a pill or liquid and is generally well tolerated.

• Thyroid hormone therapy: Taking a daily thyroid hormone pill (usually levothyroxine) on an empty stomach is necessary after removal of all of the thyroid gland (total thyroidectomy) and may be necessary after removal of only one lobe of the thyroid gland (lobectomy/hemithyroidectomy). This medication replaces the hormones your thyroid used to make and helps keep your body functioning normally. In some cases, the dose is adjusted to keep your thyroid-stimulating hormone (TSH) level slightly lower than normal, which can help prevent the cancer from returning.

• Other treatments: In rare cases where the cancer is advanced or does not respond to radioactive iodine, targeted drug therapies (such as lenvatinib, cabozantinib, selpercatinib, or dabrafenib/trametinib) may be used. These medications target specific genetic changes in the cancer cells.

What is the outlook?

The outlook for papillary thyroid carcinoma is very good. The overall 5-year survival rate is greater than 98%. At the time of diagnosis, approximately 95% of patients have cancer that is still confined to the neck, and for these patients, the 5-year survival rate is even higher.

Even among patients whose cancer has spread to distant parts of the body, younger patients (under age 45–55) often do very well, with 5-year survival rates exceeding 90%.

It is important to keep up with follow-up appointments after treatment. Your doctor will monitor you with:

• Regular blood tests (thyroglobulin and TSH levels)

• Neck ultrasounds

These tests help detect any signs of the cancer returning early, when it is most treatable. For patients at low risk who remain cancer-free for 10–15 years, ongoing monitoring for thyroid cancer may no longer be necessary.

Remember: most people with PTC live long, healthy lives after treatment. If you have questions or concerns about your diagnosis or treatment plan, do not hesitate to talk with your care team.