Papillary Thyroid Cancer

June 15, 2024 
This page was reviewed under our medical and editorial policy by Sasan Fazeli, M.D., assistant clinical professor in the Department of Diabetes, Endocrinology and Metabolism, and Karen Tsai, M.D., assistant clinical professor in the Department of Diabetes, Endocrinology and Metabolism, City of Hope^® Cancer Center Duarte.

Most people who receive a thyroid cancer diagnosis have a form of the disease known as papillary thyroid cancer. It is sometimes called papillary thyroid carcinoma (PTC) or papillary adenocarcinoma, and it accounts for an estimated 80% of thyroid cancer cases.

The thyroid is an organ located in the lower front of the neck, below the Adam’s apple, and it forms a butterfly shape. It includes two sections, which are called the right lobe and the left lobe. A majority of people diagnosed with PTC have the disease in one lobe. About 10% to 20% of people will have PTC in both lobes.

What Is Papillary Thyroid Cancer?

PTC is a slow-growing type of thyroid cancer that begins in the thyroid’s follicular cells. These cells are responsible for making thyroid hormones using iodine from the blood. Thyroid hormones affect many systems throughout the body, including helping to regulate metabolism and stimulate bone growth in children.

While PTC tumors usually grow slowly, they tend to spread to nearby lymph nodes and tissues in the neck (regional cancer) rather than stay in the thyroid itself (localized cancer). Despite PTC’s tendency to spread regionally, it typically responds well to treatment.

In addition to the main type of PTC, there are a few subtypes, including four that are less common and tend to spread quickly: tall cell, columnar, diffuse sclerosing and insular. The more common subtype, called mixed papillary-follicular variant, spreads and grows more slowly.

Metastatic Papillary Thyroid Cancer

Metastatic papillary thyroid cancer is PTC that has spread beyond the thyroid gland and nearby lymph nodes to other parts of the body. A small but significant percentage of PTC cancers are metastatic. The most common organs to which the disease spreads are the bones and lungs. The liver, brain and skin may also be affected.

Metastatic cancers tend to be more challenging to control than local or regional cancers, and treatments are tailored to address how far the disease has spread.

Papillary Thyroid Cancer Symptoms

People with PTC may not experience symptoms. Many cases are first discovered during routine physical exams or imaging for other reasons. If people do have symptoms, they may include:

• A lump in the neck, especially in the front
• Hoarseness and ongoing coughing that is not due to a cold
• Neck lymph node swelling or inflammation
• Neck pain, which may travel to the ears
• Trouble swallowing or breathing (or both)

It is important to note that because the thyroid gland tends to grow benign (noncancerous) thyroid nodules (lumps), these same symptoms may be present for reasons other than thyroid cancer. However, it is still important to see a doctor when experiencing any of these symptoms so that they may run diagnostic tests to check for potential health issues, including PTC.

What Causes Papillary Thyroid Cancer?

While there is currently no known cause of papillary thyroid cancer, changes in certain genes called oncogenes have been shown to play a part in development of the disease. These gene changes are also known as DNA mutations because they affect how a person’s DNA is arranged and operates.

Some cases of PTC develop from mutations in one of two oncogenes, known as BRAF-V600E and RAS. These mutations cause changes in a signaling pathway, which, in turn, contributes to PTC growth and spread.

Other gene changes that drive the development of PTC include the overexpression of certain genes such as RET, NTRK1 and ALK, by fusing to a partner, which then becomes active.

Most PTC gene changes occur over a person’s lifetime. These are known as acquired gene mutations.

Risk factors for PTC include those listed below.

Radiation: Head and neck radiation exposure may increase PTC cancer risk. Children have been shown to be particularly vulnerable to radiation exposure, although it may also negatively impact adults, including from radiation exposure due to nuclear plant accidents or nuclear weapons. Imaging tests that give off low to moderate levels of radiation may also contribute to a person’s risk of developing PTC cancer.

Iodine: While the risk of many follicular cell cancers increases due to low iodine intake, high iodine levels have been linked to an increased risk of developing PTC.

Being overweight or obese: Data collected between 1995 and 2015 by the National Institutes of Health-AARP Diet and Health Study linked increased body mass index (BMI) with an increased risk of PTC.

Gender: For reasons that are not clear, females are three times more likely than males to develop thyroid cancer (including the most common form, PTC).

Age: PTC is most often found in middle-aged adults. The condition is rare in children.

Race: White people develop PTC more often than Black people.

Certain genetic conditions: People who have a family history of precancerous polyps in the large intestine (called familial adenomatous polyposis or Gardner syndrome) have an increased risk of PTC. Also at greater risk are people diagnosed with two rare, inherited conditions: Werner syndrome (a disorder caused by an inherited gene mutation that causes rapid aging) and Carney complex type 1 (a disorder caused by an inherited gene mutation that causes tumors throughout the body). These inherited forms of PTC are very rare.

Family history of PTC: In a small percentage of PTC cases, family members have also been reported to have the condition.

Papillary Thyroid Cancer Diagnosis

Typically, PTC diagnosis begins with a routine physical examination at the doctor’s office or imaging done for other reasons. The doctor may notice a hard, painless lump in the neck during the exam, or a thyroid lesion in other imaging, such as a computed tomography (CT) scan, magnetic resonance imaging (MRI), positron emission tomography (PET) scan or neck doppler ultrasound. Certain PTC symptoms may also be present that indicate to the doctor that follow-up tests are needed.

These tests may include those listed below.

Fine needle aspiration: A fine needle aspiration (FNA) is a type of biopsy, which is a procedure to remove a tissue sample for laboratory analysis. FNA, a simple biopsy, is typically the first method used to diagnose PTC. As its name suggests, during an FNA, the doctor inserts a fine, hollow needle through the skin and into the thyroid nodule to remove cells and tissue. This sample is then analyzed under a microscope by a pathologist (a doctor trained in identifying diseases of the cells), who checks for cellular changes that may indicate that PTC is present.

Molecular lab tests: The doctor may also order molecular lab tests on the tissue sample to check for certain gene changes (mutations), especially if the FNA biopsy results are not conclusive.

Ultrasound: An ultrasound is the imaging test of choice for diagnosing PTC. It uses sound wave technology to help doctors discover if a thyroid nodule is solid or filled with fluid (solid tumors tend to have a higher chance of being cancerous). In addition to assisting with PTC diagnosis, an ultrasound may also be used to guide doctors during thyroid nodule biopsies.

Other imaging: Additional imaging tests may be used to confirm a PTC diagnosis, check to see how large the tumor is or determine where the cancer has spread. These include MRI scans, which use magnets to take cross-sectional pictures of the inner organs, as well as CT scans, which use X-ray radiation to take images of the inside from different angles. Additionally, FDG-PET/CT scans combine CT scans with PET scans. PET scans use a radioactive tracer substance — in this case, FDG — to visualize blood flow and other biological processes in order to help discover diseased tissues.

Blood tests: Normally, people who have PTC have normal results on thyroid function tests, so these blood tests typically are not used to diagnose the disease. However, they may be used to monitor thyroid hormone levels after PTC treatment. They include a test to check for proper levels of the thyroid hormones thyroxine (T4) and triiodothyronine (T3), as well as a test to check thyroid-stimulating hormone (TSH) levels. Other tumor marker tests, such as thyroglobulin (a protein made by the thyroid) and thyroglobulin antibody may be used to determine whether cancer cells are still present after treatment and to monitor treatment response.

Papillary Thyroid Cancer Treatment

Patients diagnosed with PTC have a variety of treatment options available to them. Their care team may recommend different options based on the size of the PTC cancer, whether it has spread and its response to prior treatments. Options include those listed below.

Surgery: Thyroid cancer treatment typically begins with surgery. If the PTC tumor is small, the doctor may decide on a thyroid lobectomy, which is the removal of just one lobe (section) of the thyroid gland. However, in most PTC surgeries, the entire thyroid is removed. This procedure is known as a thyroidectomy. Depending on how far the cancer has spread, surgery may also include the removal of the lymph nodes near the thyroid (central compartment neck dissection) or the lymph nodes throughout the neck (modified radical neck dissection). Comprehensive imaging prior to surgery helps the care team to make decisions regarding surgical options.

Thyroid hormone treatment: After thyroid removal surgery, patients may expect to take thyroid hormone therapy for the rest of their lives. The most common thyroid hormone prescribed is levothyroxine.

Radioactive iodine therapy (RAI): Since the follicular thyroid cells absorb almost all the iodine in the body, treatment with radioactive iodine may help destroy any papillary thyroid cancer cells that remain after total thyroidectomy. This treatment is typically (though not always) used for people with more advanced PTC, and it is usually only given once after the surgery (although some people require repeat treatments later on).

Thermal ablation: Destroying cancerous tissue with heat is known as thermal ablation. It may be used for smaller-sized PTC cases; however, surgery is typically preferred. One form of thermal ablation is radiofrequency ablation, which heats and destroys abnormal cells.

Targeted Therapy: If surgery and RAI treatments are not successful or PTC cancer returns, targeted therapy may be prescribed. These oral drugs specifically target mutations or fusions within the cancer cell that help it to develop cancerous properties. These drugs may block proteins that help cancer cells grow.

Before starting these treatments, a comprehensive molecular analysis on the tumor tissue is essential, which helps in selecting the appropriate targeted therapy type.

Papillary Thyroid Cancer Survival Rate

PTC is rarely fatal. Five-year relative survival rates are a statistical measure based on the number of patients with the same cancer and same stage who were still living five years or more after their diagnosis. For PTC, according to the American Cancer Society (ACS), the five-year relative survival rate varies based on how far the cancer has spread, as detailed below.

• Localized: greater than 99.5%
• Regional: 99%
• Metastatic: 74%

Because most PTC cancers are localized or regional when diagnosed, the overall five-year relative survival rate for the condition is greater than 99.5%.

These survival estimates, from ACS, are based on large amounts of data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database.

Each person is different, just like each cancer diagnosis is different. If diagnosed, a set of treatment options will be offered that are tailored to the cancer’s progression, subtype and each person’s unique treatment goals.