Although thyroid cancer first develops in the thyroid gland in the neck, it can spread (metastasize) to the lungs and other areas.

Thyroid cancer can develop when atypical cells develop in the thyroid gland. This butterfly-shaped organ at the base of the neck produces thyroid hormones that regulate metabolism, heart rate, and other vital functions.

While many cases of thyroid cancer are treatable and localized, some can spread to other parts of the body, including the lungs. This process is known as distant metastasis, which often signals advanced disease.

When thyroid cancer spreads to the lungs, it may not cause noticeable symptoms in the early stages. However, individuals may experience a persistent cough or shortness of breath.

This article explores the connection between thyroid and lung cancer, including the symptoms, diagnostic process, treatment approaches, and available resources for support.

A collage depicting the link between thyroid cancer and the lungs.Share on Pinterest
Design by MNT; Photography by Zeb Andrews/Getty Images

Thyroid cancer can spread to the lungs. However, only 1% to 4% of cases spread outside the neck to other places, such as the lungs and bone.

The spread typically occurs in cases of advanced or aggressive forms of the disease, such as some types of papillary thyroid cancer. Metastasis in the lungs is more likely when doctors do not detect or treat the disease in its early stages.

Metastasis begins when cancer cells from the thyroid gland detach from the main tumor. These cells invade nearby tissues or enter the bloodstream or lymphatic system, which acts as pathways to travel to distant parts of the body.

Once these cancer cells reach the lungs, they embed themselves in the lung tissue, where they grow and form secondary tumors.

This process may involve changes in the cancer cells that allow them to survive outside their original environment and adapt to new tissues, leading to the development of metastatic disease.

When thyroid cancer spreads to the lungs, symptoms may vary based on the extent of metastasis and the individual’s overall health. Common signs include:

  • a persistent cough that does not improve over time
  • shortness of breath, particularly during physical activity
  • chest pain or discomfort
  • coughing up blood or blood-streaked mucus (hemoptysis)
  • fatigue and unexplained weight loss
  • frequent respiratory infections or pneumonia

These symptoms can also occur with other respiratory conditions, so a person requires medical evaluation for accurate diagnosis.

Diagnosing lung metastases from thyroid cancer involves a combination of medical history, physical examinations, and diagnostic tests, such as:

  • Imaging tests: Chest X-rays, CT scans, and PET scans can detect atypical growths or nodules in the lungs.
  • Blood tests: Measuring thyroglobulin levels — a protein that the thyroid cells produce — can help monitor the spread of cancer.
  • Biopsy: A tissue sample from the lung may be obtainable through a needle biopsy or bronchoscopy to confirm the presence of thyroid cancer cells.
  • Radioactive iodine scan: This specialized scan identifies cancerous cells in the lungs that absorb iodine, a characteristic of thyroid tissue.

These diagnostic tools help clinicians determine the extent of metastasis and guide treatment planning.

Treatment for thyroid cancer that has spread to the lungs depends on factors such as the type of thyroid cancer, the size and location of the metastases, and the individual’s overall health. Common treatments include:

  • Surgery: Surgeons commonly remove the thyroid gland (thyroidectomy) and then treat the person with radioactive iodine therapy. If the metastases in the lungs are limited and accessible, surgical removal of lung tumors may also be an option.
  • Radioactive iodine therapy: This involves administering radioactive iodine to target and destroy thyroid cancer cells, including those in the lungs. It is often effective for differentiated thyroid cancers, such as papillary and follicular types.
  • External beam radiation therapy: This treatment uses high-energy rays to target cancer cells in the lungs, particularly when other therapies are ineffective.
  • Targeted therapy: Drugs that target specific genetic mutations in thyroid cancer cells, such as kinase inhibitors, can help control the spread and growth of the cancer.
  • Chemotherapy: Although a less common technique for thyroid cancer, chemotherapy may be an option for aggressive or advanced cases that do not respond to other treatments.

The outlook for individuals with thyroid cancer that has spread to the lungs varies depending on the type of thyroid cancer, the extent of metastasis, and the response to treatment.

Younger people with differentiated thyroid cancers, such as papillary and follicular types, tend to have more positive outcomes, even when lung metastases are present. This is because these cancers often respond well to radioactive iodine therapy.

The percentage of people who are alive 5 years after their diagnosis of papillary thyroid cancer that has spread to distant sites such as the lungs is 74%.

Metastatic medullary and anaplastic thyroid cancers, which are more aggressive, generally have a less favorable outlook, with a 5-year survival rate of 43% and 4%, respectively.

Facing thyroid cancer and its complications can be overwhelming, but several organizations can provide support:

Connecting with these resources can help individuals manage their condition and find community support.

Thyroid cancer can spread to the lungs, particularly in advanced cases, leading to respiratory symptoms and other complications.

Early diagnosis and targeted treatment options, such as surgery, radioactive iodine therapy, or targeted drugs, can improve outcomes for many individuals.

Resources and support networks are available to help people and their families cope with cancer and their medical care.