Lung cancer is the leading cause of cancer death and the second most diagnosed cancer in the United States for both men and women. Â Although most lung cancers are caused by smoking, never-smokers can get it too. Â Chest X-rays are not the most useful diagnostic tool for evaluating lung cancer. They often miss small lung cancer tumors that are potentially curable. But what about a cat scan (CT) of the chest? Should you be routinely screened for lung cancer using one of these high-tech contraptions? Â According to the results of the National Lung Screening Trial (NLST), that all depends.
The National Lung Cancer Screening Trial
The NLST was a lung cancer clinical trial launched in 2002. The primary results were published online in the New England Journal of Medicine in August, 2011. The main purpose of the trial was to compare two ways of detecting lung cancer: a standard chest X-ray or a low-dose, spiral CT.
The NLST enrolled 53,454 current or former heavy smokers. During the course of the trial, participants were assigned to have three yearly screening tests using either a chest X-ray or a spiral CT. Study results revealed that people who received a low-dose, spiral CT had a 15-20% lower risk of dying from lung cancer than people who were screened using a chest X-ray. Compared to the group that received chest X-rays, having a CT scan resulted in approximately three fewer deaths out of 1,000 people screened during a seven year period. 
Who Should be Screened?
After the final results of the NLSC were released, the American Cancer Society issued guidelines for lung cancer screening. They determined that you should talk to your doctor about being screened for lung cancer using a low-dose spiral CT if you meet ALL of the following criteria:
Are You in Fairly Good Health?
The purpose of screening is to detect cancer in people who donât already have signs and symptoms. If you already have symptoms, such as shortness of breath, wheeze, bloody sputum, or cough, you should see your doctor to have diagnostic (not screening) tests to determine the underlying cause of your symptoms.
According to the American Cancer Society, fairly good health is defined as being:
What if Something Abnormal is Found?
Relax! Approximately 1 out of 4 screening tests will reveal something abnormal. This doesnât mean you have lung cancer. Because CT scans are highly-sensitive, they sometimes pick up things that may initially look like cancer, but turn out to be nothing. If your doctor does find an abnormality after reviewing your scan, other tests will be ordered to rule out lung cancer. After your screening test, your doctor will discuss your results with you, and determine the right course of action.
 U.S. Cancer Statistics Working Group. United States Cancer Statistics: 1999â2011 Incidence and Mortality Web-based Report. Atlanta (GA): Department of Health and Human Services, Centers for Disease Control and Prevention, and National Cancer Institute; 2014.
 âCan Chest X-Rays Find Lung Cancer Early?â WebMD. April 8, 2005
 âNational Lung Screening Trial.âÂ National Cancer Institute. Updated September 8, 2014.