Lung nodules are small masses that grow inside the lungs. They’re very common, and at least 95% aren’t cancerous. They’re often found incidentally during chest imaging for an unrelated issue.

Long nodules are found on about 0.1% to 0.2% of X-rays and 13% of computed tomography (CT) scans in the general population. These rates increase to about 9% of X-rays and 33% of CT scans in people at a high risk of developing lung cancer, such as smokers and people with a previous cancer diagnosis.

If a doctor discovers a nodule in your lungs, they may want to track it over time to see if it gets bigger. Treatment might not be necessary if it isn’t causing symptoms and remains the same size during your follow-up appointments.

This article takes a closer look at lung nodules, including symptoms, diagnosis, and treatment.

Sizes of lung nodulesShare on Pinterest
Sizes of lung nodules. Illustration by Alyssa Kiefer.

A lung nodule is a round or oval mass of cells that’s smaller than 30 millimeters (mm) (1.2 inches) in diameter. Nodules are very common and are detected in about 1.6 million people in the United States each year. It’s possible to have a solitary lung nodule or multiple nodules.

Only about 5% of lung nodules are cancerous, but doctors often want to monitor them with imaging to make sure they don’t get bigger. Nodules that increase in size are often cancerous.

The chances of a nodule smaller than 6 mm (0.24 inches) in diameter being cancerous is less than 1%. The odds increase to about 1% to 2% for nodules of 6 to 8 mm (0.31 inches). The risk is more than 2% in nodules larger than 8 mm.

Doctors almost always recommend CT surveillance for nodules between 6 and 8 mm in diameter. Larger nodules are often monitored with:

About 95% of people with a lung nodule diagnosis don’t have symptoms. They’re often discovered incidentally during imaging for unrelated conditions. When symptoms do appear, they can cause:

According to the American Thoracic Society, lung nodules are usually caused by:

  • scar tissue
  • a healed infection
  • an irritant in the air

Less commonly, nodules are caused by an inflammatory disease like rheumatoid arthritis or are cancerous growths.

A 2018 study that studied 7,752 people in northern China found the following risk factors for lung nodules:

  • increased age
  • smoking
  • secondhand smoke exposure
  • dust exposure
  • history of lung disease
  • family history of cancer

Factors associated with a lower risk were higher consumption of:

  • vegetables
  • legumes
  • tea

Lung nodules are often discovered incidentally on X-rays or CT scans of the chest. CT scans are most likely to reveal nodules and can detect changes in their size as small as 1 to 2 mm.

Small nodules

If you have a nodule smaller than 6 mm, a doctor may tell you that no follow-up is needed. Doctors sometimes recommend a follow-up 12 months later for people at a high risk of developing lung cancer.

Medium nodules

For nodules between 6 to 8 mm, doctors often recommend another CT scan after 6 to 12 months and again at 18 to 24 months if necessary.

Large nodules

If you have a nodule larger than 8 mm, doctors often recommend another CT scan after 3 months. If it has grown, a doctor might want to run a PET/CT scan. This test combines a CT scan with a PET scan. A PET scan uses a special camera to detect small amounts of radioactive dye injected through an intravenous (IV) line.

If the PET/CT scan suggests that it’s cancer, a doctor will likely want to take a small tissue sample with a biopsy.

A biopsy can be performed in three ways:

  • with a long tube down your throat called a bronchoscope
  • with a thin, hollow needle through your chest wall with CT guidance
  • surgically by removing part of your lung

Small, noncancerous nodules usually don’t need treatment, but a doctor may still want to monitor them over time. If nodules grow large enough to cause problems or are cancerous, you may need to have them surgically removed.

Surgical options include:

  • Open thoracotomy: During an open thoracotomy, a surgeon makes a large incision between your ribs to access your lung.
  • Video-assisted thoracic surgery (VATS): During VATS, a surgeon uses a thin tube called a thoracoscope with a camera to see inside your chest and make an incision. It’s considered a minimally invasive procedure.
  • Robotic-assisted thoracoscopic surgery (RATS): During RATS, a surgeon guides a small robotic arm through a tiny incision in your ribs to remove the nodule. It’s also considered a minimally invasive procedure.
  • Stereotactic body radiotherapy: Stereotactic body radiotherapy uses a concentrated beam of radiation to destroy cells. It may be recommended if you have stage I non-small cell lung cancer.
  • Radiofrequency ablation: Radiofrequency ablation uses radio waves to create heat to destroy the nodule.

The biggest factor that affects your outlook is whether nodules are cancerous. Small lung nodules that aren’t cancerous normally don’t affect your quality of life.

In a 2020 study, researchers found that the 3-year overall survival rate of people with cancerous solitary nodules was 93.6% and that the 5-year overall survival rate was 89.8%.

Early detection and treatment give you the best chance of treating cancer before it spreads.

Can lung nodules appear after a SARS-CoV-2 infection?

Some people develop lung nodules from an infection with SARS-CoV-2, the virus that causes COVID-19. The incidence rate of nodules on CT scans of people with COVID-19 has been reported as 3% to 12%.

What is a ground-glass lung nodule?

A ground-glass nodule is a nodule that appears hazy on a CT scan. They’re associated with lung adenocarcinoma.

What is a calcified lung nodule?

A calcified nodule contains calcium and is usually easily picked up during imaging. Most aren’t cancerous, and they often occur after a lung infection.

Can I get a lung nodule if I don’t smoke?

It’s possible to develop lung nodules even if you don’t smoke. Factors like previous respiratory infections can cause them to develop.

Do lung nodules need to be removed?

Smaller nodules often don’t need to be removed, but a doctor may recommend regular follow-ups to make sure they don’t get bigger over time. Nodules that are cancerous or likely cancerous usually need to be removed.

Lung nodules are small growths that form in your lungs. They’re common and usually not cancerous.

Lung nodules are often discovered when you receive imaging for an unrelated condition. If a doctor discovers that you have a nodule, they may recommend follow-up scans to see how it changes over time. If they think it’s cancerous, they may recommend removing it surgically.