Screening means testing for a disease before any symptoms begin, or because a person has a history of the disease. The aim of screening is to detect a disease at its earliest and most treatable stage. A screening test must meet certain criteria, including reducing the risk of death from the disease, in order to be recommended by medical practitioners.

Screening tests may include laboratory tests, genetic tests, and imaging tests. However, an individual’s need for a specific screening test is based on factors such as age, gender and family history.

In the case of cancer, the appearance of symptoms is sometimes preceded by the progress of cancer to a late stage so doctors recommend a screening test to detect it at an early stage when treatments may work better.

The only recommended screening test for individuals who have a high risk of developing lung cancer, but who have no signs or symptoms of the disease, is low-dose computed tomography (LDCT) scanning of the chest.

Other tests such as chest X-ray (X-ray scanning of the chest) and sputum cytology (microscopic examination of the mucus coughed up from the lungs) usually are not recommended as screening tests because they do not meet the criteria of reducing the risk of dying from lung cancer.

LDCT scan

Screening with low-dose CT scan is better at finding early-stage lung cancer and has been shown to decrease the risk of dying from lung cancer in heavy smokers.

In this test, special X-ray equipment is combined with sophisticated computers to produce multiple, cross-sectional images of the inside of the body. Numerous X-ray beams and a set of electronic detectors rotate around the person, measuring the amount of radiation being absorbed throughout the body. At the same time, the examination table is moving through the scanner so that the X-ray beam follows a helical path.  LDCT scan produces images of sufficient quality to detect many abnormalities using up to 90 percent less ionizing radiation than a conventional CT scan.

If a screening test result suggests cancer, diagnostic tests are required to confirm the presence of lung cancer.

Who should be screened?

The U.S. Preventive Services Task Force recommends annual screening for lung cancer with LDCT for adults who:

  • Are between 55 and 80 years old;
  • Have a heavy smoking history of at least 30 pack years (an average of one pack of cigarettes per day for one year), and;
  • Smoke currently, or have quit within the past 15 years.

Risks of screening

Lung cancer screening has several risks:

  • A lung cancer screening test may appear abnormal and suggest the presence of cancer even though no cancer is present. This is called as a false-positive result. This can cause anxiety and lead to unnecessary follow-up tests and surgeries that may have more risks.
  • A lung cancer screening test may appear normal and suggest the absence of any cancer even though cancer is present. This is called a false-negative result. This may delay appropriate medical treatment even if there are symptoms.
  • A lung cancer screening test can lead to the diagnosis of cancer that may have never caused a problem for the patient, leading to cancer treatment that is not needed.
  • Radiation exposure from repeated LDCT tests may damage lungs and increase the risk of cancer in otherwise healthy people.

So, lung cancer screening is recommended for only adults who have no symptoms, but are at high risk of developing the disease due to their smoking history and age.

The best way to reduce the risk of lung cancer is to completely avoid smoking, including secondhand inhalation of smoke. Lung cancer screening is not a substitute for quitting smoking.

When should screening stop?

The U.S. Preventive Services Task Force recommends that the annual lung cancer screening should stop when the person being screened:

  • Turns 81 years old, or;
  • Has not smoked in 15 years, or;
  • Develops a health problem that makes him or her unwilling or unable to have surgery if lung cancer is found.


Note: Lung Cancer News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.