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Lung nodules are not always something to worry about, but they can be alarming to see on a CT scan
Lung nodules can form due to various causes, such as inflammation or infection, and are not always cancerous. Small lung nodules (less than 3 cm) are usually not a cause for concern, while larger nodules (greater than 3 cm) may be more worrisome. Studies have shown that only 3-4 out of a 100 lung nodules are cancerous.
Lung nodules are often found when computer tomography (CT) scans or chest X-rays are done to evaluate other lung conditions. Although most lung nodules are benign, even small ones should be assessed to rule out cancer. Early detection and treatment for cancer leads to a better prognosis.
What causes lung nodules?
Benign lung nodules may be formed due to scarring of lung tissue caused by tuberculosis or fungal infections. Recently, lung nodules have been noted in many patients infected with COVID-19.
Cancerous nodules are the earliest stage of primary lung cancer. They can also be a sign of secondary cancer that has spread to the lungs from another area of the body.
Other causes of lung nodules include:
- Inflammatory conditions, such as sarcoidosis or rheumatoid arthritis
- Hamartoma (benign growth made up of an abnormal mixture of cells and tissues normally found in the lungs)
- Exposure to or inhalation of hazardous chemicals (occupational exposure), such as asbestos, cigarette smoke, and other carcinogens
Do lung nodules cause symptoms?
Lung nodules typically do not cause symptoms, unless the underlying cause is due to infections or cancer. Symptoms may include:
- Persistent cough
- Coughing up blood
- Shortness of breath
- Wheezing
- Fever
How do doctors determine whether a lung nodule is benign or cancerous?
Several indicators are considered to determine whether a lung nodule is benign or cancerous:
- Size: Larger nodules are more likely to be cancerous than smaller ones.
- Shape: Nodules that are smooth and spherical are more likely to be benign, but irregular or spiculated nodules are more likely to be malignant.
- Calcification: Calcified lung nodules are more likely to be benign.
- Cavitation: Cavitary nodules are more likely to be benign, although they can be malignant as well.
- Growth: Cancerous lung nodules develop rather quickly, with an average doubling time of roughly 4 months, but benign nodules tend to remain the same size over time.
- Age: Lung nodules in people younger than 35 are usually benign. About 50% of lung nodules in people older than 50 are cancerous.
- Previous medical history: History of cancers or radiation exposure raises the probability of cancerous lung nodules
- Occupation: Certain occupational exposures, such as asbestos, increase the chances of a nodule to be cancerous.
- Smoking: History of smoking and secondhand smoking increases the risk of lung nodules being cancerous.
Based on the likelihood of cancer, more tests may be needed to make a diagnosis.This might involve a positron emission tomography scan, a biopsy, or more computed tomography scans to monitor the lesion.
What are risk factors for lung cancer?
Common risk factors of lung cancer include:
- Family history: If a close relative such as a parent or sibling has a history of lung cancer, you may be at risk.
- Smoking: The number of years you have smoked and the number of cigarettes you smoke each day can dramatically raise your risk of lung cancer.
- Second-hand smoke: Even if you do not smoke, being around smokers could put you in danger of developing lung cancer.
- Prolonged radon exposure: Although radon exists naturally, hazardous amounts in your home, office, or buildings you visit can raise your risk of lung cancer.
How can you minimize your risk of lung cancer?
According to the Centers for Disease Control and Prevention, cigarette smoking is the leading cause of lung cancer in the United States, responsible for up to 90% of lung cancer deaths. If you smoke and develop lung nodules, you should stop smoking immediately.
Quitting smoking can help reduce your chance of developing lung cancer and other health issues, such as chronic bronchitis, rheumatoid arthritis, heart disease, stroke, and emphysema.
Timely assessment of lung nodules and appropriate treatment are crucial. Not all benign lung nodules require active treatment. However, suspicious nodules or cancerous nodules must be treated, often through surgical removal.
