Are Lung Nodules Serious?
A lung nodule is a small round growth on the lung that should be considered serious because it could be a type of early stage cancer. As precaution, every doctor will observe these growths as malignant (cancerous), until they have sufficient proof that it is benign (not cancerous).
To make this distinction, they may run a series of tests:
- Check the patient’s medical history. Nodules may appear as left over wounds from other infections and illnesses (link) which may indicate that the nodule is benign. On the other hand, a prior history of cancer will increase the chance of the nodule being malignant.
- Check the patient’s age. Risk of malignancy seems to increase with older age. It is estimated that patients under 35 years old have approximately less than 1% chance of the nodule being malignant whereas people over 50 have an incidence rate of 60%.
- Check the patient’s work environment and personal habits. A history of smoking or an exposure to asbestos, nickel and other known causes of lung cancer will increase the chance of the nodule being malignant.
- Observe the growth rate of the nodule through a series of CT scans. Benign nodules will not grow. However, malignant nodules can double in size in as little as 15 days and as slow as 450 days. Nodules larger than 3cm in diameter are deemed masses, and have a significantly higher probability of being malignant.
- Observe the level of calcification. Benign nodules will have the presence of calcification (speckled or “popcorn” pattern) with smooth rounded edges or borders.
- Retrieve cells from the nodule to perform a biopsy. A biopsy is a medical procedure where a sample of tissue is taken from the patient for further examination by a pathology laboratory. This procedure can identify abnormal cells.
- PET scans. Positron emission tomography is able to differentiate between malignant and benign nodules with 95% sensitivity by measuring 18-fluorodeoxyglucose (FDG). FDG is injected into the patient and then the PET scanner can form images of the distribution of FDG around the body. Malignant cells have an increased FDG uptake and tend to metabolise the glucose at a faster rate than benign tumours. However this scan is known to produce false results when nodules are in an active inflammatory process due to other non cancerous causes.
The overall probability that a nodule is malignant is estimated at 40%.
Prompt diagnosis and prompt treatment of malignant nodules may be the only chance to cure the possible cancer.