What Kinds of Tests Are Used to Diagnose Lung Cancer?
Your doctor may suspect a predisposition to lung cancer based on your medical, family and smoking history. He may note wheezing, difficulty breathing, obstruction of the airways or infections in the lungs that make him suspicious. There are other signs he may notice that lead him to decide to test further to rule out or diagnose lung cancer.
Chest X-ray
The first test that most doctors order when they suspect any sort of lung condition is a chest x-ray. In most cases, the technician will take both back to front and side views to give a good view of the lungs from different angles. A specialist will study the chest films for any signs of lesions, spots or other suspicious areas on the lungs. A chest x-ray alone isn’t enough to diagnose lung cancer, but it can show suspicious areas and growths to investigate further.
CAT Scans
A CAT scan (also called CT scans) may be ordered if x-rays are negative or ambiguous. Cat scans give a more detailed view of the lungs by combining multiple views to create a cross-section of the body. In addition to views of the lungs, a doctor may order CAT scans of the abdomen or brain to examine for metastatic tumors. CAT scans are more sensitive than standard chest x-rays, and may reveal lung masses that are missed on x-rays.
A special type of CAT scan is sometimes ordered if more detail is needed. The low-dose helical CT scan (or spiral CT scan) is far more sensitive than either x-rays or standard CAT scans. However, like both of those, it can’t detect cancer – only abnormal formations in the lungs. About 90% of the growths discovered in a spiral CT scan are non-cancerous.
The doctor may also order MRI (magnetic resonance imaging) to obtain detailed information about the location of a tumor. Because MRIs use magnets, anyone with a pacemaker, artificial heart valves or any other surgically implanted device can’t use MRI, to avoid the metal parts ‘attracting’ the magnets in the MRI.
PET Scans
While CAT scans and x-rays can determine size and location of a tumor, PET scans can determine whether the tumor is actively growing. By using a radioactive dye, a PET scan (positron emission tomography) produces a three-dimensional colored image that can show the metabolic activity within the lungs. By studying those images, doctors can tell whether a tumor is active, and may be able to identify the types of cells that make it up.
Sputum cytography
By examining a sputum sample under a microscope, a doctor may be able to detect cancerous cells that will positively diagnose lung cancer, as well as tell the doctor what kind of cancer it is. Sputum cytography is the least expensive type of tissue diagnostic test available, but it is not very reliable. Even if there is lung cancer present, the cancer cells may not be present in the sputum. In addition, there’s a possibility of false positives, as non-cancerous can sometimes change in reaction to injury or illness and appear to be cancerous.