A solitary pulmonary nodule (SPN) is an abnormal growth in
the lung. Often a person who has an SPN does not have any respiratory symptoms.
A chest X-ray or CT scan done for some other reason usually detects an SPN.
An SPN found on a chest X-ray does not mean
lung cancer is present. A past lung infection can
cause a noncancerous SPN. But of all SPNs doctors think might
be cancer and have tested with a
about 40% to 60% are cancerous.1 Noncancerous SPNs
often are caused by a previous infection in the lung. Further tests can be done
to find out whether the SPN is noncancerous (benign) or cancerous
CT scan normally is done to help find out the growth
rate, the shape of the nodule, and the pattern of calcification in the nodule
to help identify whether it is cancerous.
Positron emission tomography (PET) scans are being
studied to find out whether they can help distinguish between noncancerous and
In general, the larger the SPN, the more likely it
is to be cancerous. A very small SPN has less than a 1% chance of being
cancerous. The risk increases to 80% for a large SPN.2
Your doctor may use a probability
of cancer (PCA) table to help determine the risk that an SPN is cancerous. Then
he or she may recommend follow-up testing with a biopsy or regular CT scans or,
if it is very likely the SPN is cancerous, the doctor may suggest finding out
its stage and removing it with surgery.
The following table shows
when solitary pulmonary nodule is likely or not likely to be cancer. None of
these are true in every case, but these factors are used to help decide whether
further testing or treatment is needed.1
Solitary pulmonary nodule: Is it likely to be cancer?
| It's probably not cancer|| It's probably cancer|
- You are younger than 35.
nodule is smaller than
2 cm (0.8 in.).
nodule edge is smooth and regular.
- You have never
- The nodule has thick areas
- You have a history of
- You have a history
of exposure to
tuberculosis (TB) or a fungal
- The nodule either grows very quickly or does not grow
much over 2 years.
- You are older than 50.
nodule is bigger than
3 cm (1.2 in.).
nodule edge is irregular or jagged.
- You are a smoker. The more you
have smoked, the more likely the SPN is to be cancer.
- The nodule
does not have thick areas.
- You have a history of exposure to
asbestos, radiation, or radon.
- You have a history of
- The nodule grows bigger at a
moderate, steady rate.