Lung cancer remains the single largest cause of cancer death in the United States, resulting in over 162,000 deaths in 2006, the National Cancer Institute states. Many lung cancers are not detected until they've already metastasized, or spread to other areas. Around 85 percent of lung cancers occur in smokers or ex-smokers, according to the Merck Manual. While computerized tomography, or CT scanning, can diagnose early lung cancers, CT scans still aren't routinely used a screening tools for smokers.
Method
CT lung scans produce multiple cross-sectional pictures of the tissue, bones and blood vessels using 65 percent less radiation than conventional X-rays, RadiologyInfo.org reports. CT scans cause no pain, but claustrophobic people may find being in the CT machine, which is a large tube, difficult. The person having the test lies flat and a machine that rotates around them takes the scans. A spiral CT, which takes multiple slices in a single rotation, scans the entire chest within 12 to 20 seconds, according to the National Cancer Institute.
Timing
CT scans are usually done when medical personnel suspect a person has cancer, but have also been done as a screening test. However, while CT scan diagnosed three times as many cancers as expected, they also resulted in 10 times as many surgeries as expected, the Mayo Clinic states. CT scans did not reduce the number of deaths from lung cancer or the number of people diagnosed with advanced cancer, and risks may not outweigh the benefits. Many cancers diagnosed were slow growing and may never have caused any problems.
Results
Between 20 and 60 percent of all smokers will have abnormalities on a lung CT, David Midthun, M.D. of the Mayo Clinic states, but most of these represent scarring, inflammation and other non-cancerous abnormalities. Biopsying these areas can cause damage to the lung, so many physicians advocate waiting and rechecking the lung with another scan in a few months to a year. Around 50 percent of those scanned have one or more very small nodules that don't need immediate treatment but do need follow-up to assess for changes that may indicate cancer.
Interpretation
Because CT scan are so sensitive, results must be interpreted by medical personnel. A radiologist reads the scan and sends a written report to the ordering physician.
Considerations
CT lung scans are so sensitive that they record many abnormalities that aren't cancer, but may require follow-up. Several studies on the possible benefit of screening scans are currently being conducted, but presently, no organization advocates routine CT screening for smokers. Instead of using CT for screening, the Mayo Clinic suggests stressing quitting smoking, the major cause of lung cancer, Midthun states. However, for suspected lung cancers, CT scans are an effective diagnostic tool.
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