Lung nodules are small masses of tissue in the lung that appear as round, white shadows on a chest X-ray or CT scan. They are usually 5 mm to 25 mm in size, with the larger nodules (>25 mm) more likely to be cancerous than the smaller ones.
Lung nodules are actually quite common, and most of them are benign, or noncancerous. Some, however, are suspicious enough to warrant further investigation or follow-up cancer.
Once detected by means of a chest X-ray or a CT scan, a physician will be able to compare a lung nodule’s size with later scans. If the nodule appears to remain the same size, it is likely not cancerous.
Causes of Lung Nodules
Benign lung nodules can be caused by a number of conditions:
- Lung infections such as tuberculosis or histoplasmosis
- Lung cysts
- Small collections of normal cells (hamartoma)
Malignant (cancerous) lung nodules are the result of cancers that either start in the lungs or spread to the lungs from a cancer elsewhere in the body.
Detection & Treatment
When a lung nodule is detected, your doctor will decide how to evaluate it based on its size, location and appearance.
An additional scan called a Positron emission tomography (PET) scan may help your doctor make better treatment recommendations.
The PET scan will light up the nodule if it is rapidly growing or active. The brighter the nodule appears on the PET scan, the more likely that it is cancer. The PET scan also looks at the rest of the body and can identify if the cancer has spread.
If the nodule is very suspicious for cancer, your doctor may recommend a biopsy or even surgical removal as long as there are no signs of spread elsewhere in the body.
If the nodule is more likely benign based on its appearance and is small, your doctor may recommend periodic checks using a CT scan.
These scans are usually repeated every 3 to 6 months for a 2-year period. If the nodule does not change during that time, it is likely benign and needs no further treatment.
If results of the CT scan and PET scan are inconclusive, a biopsy of the nodule may be performed in order to determine the nature of it.
Biopsy of Lung Nodules
If the nodule is considered suspicious based on the CT scan, whether because of its size, shape, or appearance, a biopsy may be taken to determine whether or not it is cancerous (malignant). There are several different ways in which a biopsy can be performed.
If the nodule is near the airways, your doctor may use a bronchoscope to perform the biopsy. The bronchoscope is a flexible tube with a small camera which is used to look through your mouth or nose into the airways. Tiny instruments are then used to take a biopsy. This procedure is done either in the operating room or a special bronchoscopy suite and you should be able to go home the same day.
If the nodule is near the edge of the lung, a radiologist may be asked to biopsy the nodule using a CT scan as a guide. The biopsy is performed by numbing the skin near the nodule and using a needle to remove some cells from the nodule. With either type of biopsy, the cells removed will be given to the pathologist who can determine whether or not the sample contains cancer.
After the pathologist determines whether or not the sample is malignant, your doctor will determine the next course of action. If it is benign, your doctor will merely examine the nodule periodically with CT scans, to determine whether any changes occur in it. If it is malignant, your doctor will perform more tests to determine whether it has spread, and what course of treatment is recommended.
Treatment of Lung Nodules
In cases of benign lung nodules, no treatment is necessary. If a nodule is cancerous, your doctor will perform other tests to determine if it has spread anywhere else in the body. If it is only in the lung, surgical removal is the usual treatment. This is why early detection is so useful in treating malignancies—if caught early enough, before they have spread, the prognosis is better for the patient.
If the nodules have spread to other parts of the body (metastasized), then a greater course of treatment is necessary, typically radiation therapy, chemotherapy, or combination therapy.
Lung Cancer Screening
The National Lung Cancer Screening Trial is the first scientific study providing clear evidence that the low-dose helical computed tomography (CT) scan is an effective screening technique and significantly reduces death due to lung cancer in heavy smokers.
If you are concerned about lung nodules, lung cancer or other lung diseases, please contact your physician to discuss ways to reduce your risk and whether you should undergo lung cancer screening with a low-dose helical CT scan.
If you do not have a physician, you may request an appointment with one of our physicians at Northwestern Memorial Hospital by calling our Physician Referral Service at 1-877-926-4664. You may also request a first time appointment online.