If your doctor tells you about a lung nodule (a spot on your lung) after a chest X-ray or CT scan, you may feel anxious to know what it means. But these nodules are a common finding in imaging tests, showing up in about 30% of all CT scans of the chest.
Most lung nodules don’t mean you have cancer. But if the spot does point to cancer, catching it early gives treatment a chance to work, with much better results.
Your Scans Show a Lung Nodule: Now What?
On a scan, a lung nodule (also called a pulmonary nodule) looks different from the area around it — like a round white shadow. Many people learn they have a lung nodule after getting a lung cancer screening test or a scan for some other reason.
“The vast majority of lung nodules are not cancer,” says Stephen Baldassarri, MD, an assistant professor of medicine at the Yale School of Medicine in New Haven, Connecticut. “Some are though, which is why we need to pay attention when a nodule is discovered and take the issue seriously.”
The next steps can include future monitoring or more testing to find out more about the nodule. Once you know, you and your doctor can create an action plan.
Why You Might Have a Lung Nodule
Anything from a lung infection to chemicals in the air can create a nodule. There are many risk factors for lung nodules.
“Most nodules are quiet remnants of battles your immune system already won years ago,” says Michael Zgoda, MD, an interventional pulmonologist at City of Hope Cancer Center Phoenix in Goodyear, Arizona.
A spot on your lung could be:
- A previous lung infection scar (most common)
- Scarring from smoking or breathing in toxic chemicals
- Inflammation from an autoimmune diseases like rheumatoid arthritis
- Noncancerous growth (benign tumor)
- Cancer (malignant tumor)
Out of all lung nodules found, only 4% turn out to be cancerous. But some things can increase your cancer risk.
What makes problems more likely?
If your doctor spots a lung nodule on your scan, they'll ask you about any risk factors for lung nodules that may point to cancer, such as:
- A smoking history (packs per day for how many years)
- Past cancer or family history of cancer
- Exposure to radon, asbestos, arsenic, and fuel exhaust
- Chronic obstructive pulmonary disease (COPD) or emphysema
- Prior radiation therapy to your chest
- Age older than 65
“Lung cancer is much more likely to occur in individuals with risk factors, and your doctor will factor this in when assessing a lung nodule,” Baldassarri says.
Besides risk factors, your symptoms can also provide clues. Most nodules don’t cause any symptoms, says Laurie Matt-Amaral, MD, a medical oncologist at Cleveland Clinic Akron General in Akron, Ohio.
“Most patients don’t even know they’re there until a screening exam picks them up,” she says.
But other nodules cause symptoms that may point to something active and potentially serious, such as cancer or infection, says Zgoda. These symptoms include:
- Chest pain
- Trouble breathing
- Wheezing
- Coughing up blood
- Persistent cough
- Feeling exhausted
- Hoarse voice
- Poor appetite
- Lung infections that keep coming back
Understanding Your Lung Nodule Report
With online medical records, you may have access to your lung scan report, but complex medical terms can leave you feeling just as confused and anxious. And although your report won’t be written out in simple language, learning the medical terms below can help you understand it.
A CT scan report has several sections:
- Indication: What they’re looking for
- Technique: How they did it
- Comparison: Based on past scans
- Findings: A description of what they found
- Impression: A summary of what the findings might mean
- Recommendation: Next steps
When your doctor reads your test results, they’ll look for the nodule’s size, shape, and density (how solid it looks). On your lung nodule report, you may see the common terms below. Here’s how our experts describe them.
You may also see words like diffuse, central, lamellated, and popcorn, which describe noncancerous types of calcified nodules.
Even with the glossary above, reading a medical report can be overwhelming. If you come across a word or phrase you don't understand, highlight it to ask about later. Zgoda tells his patients to ask every single question that comes to mind. You can also bring someone with you to appointments to take notes.
How much does the size of your nodule matter?
Nodule size matters, and larger spots may prompt faster follow-up, says Michael Jones, MD, a hematologist with SSM Health Cancer Care in Fond du Lac, Wisconsin.
“Simply put, the larger the size of a pulmonary nodule, the greater the risk of cancer,” he says.
Doctors measure lung nodules by diameter (from one side to the other) in millimeters (mm), which you can usually find on your scan report.
Nodule Size | Percentage of Nodules That Are Cancerous |
| Smaller than 5 millimeters | Less than 1% |
| 5-9 millimeters | 2%-6% |
| 8-20 millimeters | 18% |
| Larger than 20 millimeters | More than 50% |
“The most important clue is growth over time on follow-up scans,” Zgoda says.
But size doesn’t give you the whole story.
“If you’re a heavy smoker over age 55 and the nodule is larger than 8 millimeters with irregular edges, that risk can climb to 15%-20% or higher,” he says.
How Doctors Decide What Happens Next
Once you have your scan results, your doctor will talk with you about the next steps. This may involve:
- Asking about your medical history and cancer risk factors
- Doing a physical exam, like listening to your lungs with a stethoscope
- Pulmonary function tests to see how well your lungs move air in and out
- Looking at past CT scans or chest X-rays
Future scans and treatment depend on what your nodule looks like and how many risk factors you have.
“If the nodule looks small and low-risk, we monitor it with repeat scans at set intervals, usually three to 12 months, depending on the guidelines,” Zgoda says.
If it’s bigger or has suspicious features (like spiky edges), you may need some other tests.
Tests used to diagnose or rule out lung cancer include:
- A CT scan, a specialized type of X-ray that shows your lungs in “slices,” as if you’re viewing them from the top down
- A PET scan, which uses images taken after safe radioactive chemicals are injected into your bloodstream to get a more detailed view of your lungs
- Fluid tests, which are done on blood or sputum (spit) that can identify infections or other nodule causes
- A biopsy, the surgical removal of a piece of or an entire nodule to test it for cancer or other conditions
Only a biopsy can diagnose lung cancer, but the other tests above can help your doctor decide if you need one.
Solid nodules typically need follow-up scans for at least two years.
“A solid nodule that hasn’t grown in two years is very unlikely to be cancerous,” says Baldassarri.
But partially solid nodules may be monitored for longer.
How long will it take to know if my lung nodule is cancer?
Few medical tests offer instant results, and it may take anywhere from one day to a few weeks to get results from a lung nodule test. The timing depends on the test, your doctor, and, sometimes, how busy the testing center is at the time.
But because early diagnosis and treatment can make a vast difference in lung cancer outcomes, your doctor should get in touch soon if they see any signs of cancer.
Do All Lung Nodules Need Treatment?
Not all lung nodules need treatment.
“Treatment only starts when we have strong evidence the nodule is malignant or is causing real problems such as bleeding, obstruction, or infection,” Zgoda says.
Some nodules heal on their own, and those caused by an infection can be taken care of with antibiotics or antifungals. For nodules with a low cancer risk, you may only need monitoring over time to check for growth.
But lung nodules with a high risk of being cancer need a more aggressive approach, says Baldassarri. The treatment approach in this case may include:
- PET scans to look for chemical activity in the nodule
- A lung biopsy to plan targeted treatment
- Surgery to remove the nodule
Your doctor may also refer you to a lung specialist (pulmonologist) to recommend a treatment.
Will Lung Nodules Get Worse?
Lung nodules that look benign at first can grow over time. But follow-up scans ordered by your doctor can catch these changes quickly.
New or worsening symptoms can also mean your lung nodule has changed. Let your doctor know if you have symptoms like trouble breathing or a cough that doesn’t get better.
