Lung nodules are small growths in your lungs, less than 30 millimeters in diameter. Many nodules aren’t cancerous, but the risk becomes higher with increased size.
A lung nodule is an irregular growth in your lungs that has a diameter of less than 30 millimeters (mm), or 1.2 inches.
Lung nodules are very common and are estimated to occur in
Most lung nodules aren’t cancerous. Possible noncancerous causes include:
- infections
- rheumatoid arthritis
- benign lesions (such as hamartomas)
Nodule size and growth rate, along with shape and pattern of calcification, determine a nodule’s risk of being cancerous.
Small nodules often don’t require treatment. Doctors may recommend follow-ups or surgery for large nodules, especially if you are at a high risk of developing lung cancer.
This article reviews lung nodule sizes and recommended treatments.
Most nodules don’t cause symptoms and don’t need treatment. Larger nodules are more likely to be cancerous and require surgical removal.
The
The Fleischner Society guidelines advise doctors on how to manage lung nodules based on factors such as:
- nodule size
- rate of nodule growth
- tissue composition of the nodule
The guidelines don’t apply to people who are younger than 35 years old or have a history of cancer or immunosuppression.
What’s considered a small lung nodule?
Lung nodules are usually considered small if they’re less than
Here’s a look at the risk that small nodules will become cancerous:
| Diameter | Risk of being cancerous |
|---|---|
| 1 to 2 mm | These nodules are routinely found and have a very small risk of being cancerous. |
| less than 6 mm | Research suggests that these nodules have an 0% to 1% chance of being cancerous. |
| 6 to 8 mm | These nodules have a |
| more than 8 mm | These have about a |
| more than 10 mm | These have about a |
What’s considered a large lung nodule?
Large nodules are those more than 10 mm in diameter. The risk of nodules being cancerous increases as they become larger. By definition, a nodule is smaller than 30 mm.
| Diameter | Risk of being cancerous |
|---|---|
| more than 10 mm | These nodules have about a |
| more than 30 mm | These are considered lung masses and are |
If you’re at low risk of developing lung cancer, a doctor will likely tell you that you don’t need regular follow-ups for nodules smaller than 6 mm. Younger age and a lack of smoking are associated with low risk. A doctor may want to follow up with a CT scan if you’re at high risk.
A doctor will likely want to monitor nodules that are
For nodules larger than 8 mm, a doctor will likely want to follow up with some combination of:
- repeated CT scans
- a positron emission tomography (PET)/CT scan
- a tissue biopsy
The next step depends on:
- the nodule’s size
- the number of nodules a doctor finds
- the tissue features of the nodule
Depending on how nodules look on a CT scan, doctors classify them as either solid or subsolid. Subsolid nodules can be further classified as ground-glass or part-solid.
Here’s a look at the Fleischner Society guidelines for each type.
Recommendations for a single solid nodule
| Size | Treatment |
|---|---|
| smaller than 6 mm | • Low risk: no routine follow-up needed • High risk: optional CT scan at 12 months |
| 6 to 8 mm | • Low risk: CT scan at 6 to 12 months and possibly at 18 to 24 months • High risk: CT scan at 6 to 12 months and again at 18 to 24 months |
| larger than 8 mm | CT scan at 3 months and possibly PET-CT scan or biopsy |
Recommendations for multiple solid nodules
| Size | Treatment |
|---|---|
| smaller than 6 mm | • Low risk: no routine follow-up needed • High risk: optional CT scan at 12 months |
| 6 mm or larger | • Low risk: CT scan at 3 to 6 months and possibly at 18 to 24 months • High risk: CT scan at 3 to 6 months and again at 18 to 24 months |
Recommendations for a single subsolid nodule
| Size | Treatment |
|---|---|
| ground-glass nodule smaller than 6 mm | no follow-up required |
| ground-glass nodule 6 mm or larger | • CT scan at 6 to 12 months • CT scan every 2 years for 5 years if nodules persist |
| part-solid nodule 6 mm or larger | • CT scan at 3 to 6 months • CT scan every year for 5 years if the solid component remains smaller than 6 mm |
Recommendations for multiple subsolid nodules
| Size | Treatment |
|---|---|
| smaller than 6 mm | • CT scan at 3 to 6 months • if stable, CT scan at 2 to 4 years in high risk people |
| 6 mm or larger | • CT scan at 3 to 6 months • management based on the most suspicious nodule |
A doctor may recommend a biopsy if repeat CT scans show that the nodule is getting bigger over time or has concerning features.
A biopsy can be performed in
- with a bronchoscope (a long tube that goes down your throat)
- with a hollow needle through your chest wall with CT guidance
- with surgery to remove the nodule and surrounding lung tissue
Risk factors for the development of cancerous lung nodules
- smoking
- increased age
- prior lung infection
- history of cancer
- interstitial lung disease
- emphysema
- exposure to chemicals such as asbestos, radon, and uranium
You may be able to minimize your chances of developing lung nodules by quitting smoking if you currently smoke or by avoiding smoking if you don’t. This can be difficult, but a doctor can create a cessation plan that works for you.
Minimizing your exposure to cancer-causing substances, such as uranium, and wearing proper safety equipment if you handle them may also lower your risk.
Lung nodules are small growths in your lungs, less than 30 mm in diameter. Most nodules are not cancerous, but the risk increases as they become larger.
A doctor may want to perform regular follow-ups for nodules larger than 6 mm or for smaller nodules if you have a high risk of lung cancer.
A doctor may recommend a biopsy or surgical removal of nodules that are growing or have concerning features.