Content Map Terms

Lung Cancer Screening

British Columbia Specific Information

Low dose computed tomography (CT) scans search the lungs for signs of lung cancer, as well as other lung diseases. Early detection using low dose CT scanning has been shown to reduce lung cancer deaths by 20%. The BC Lung Screen Trial provides the only access to organized lung cancer screening to eligible B.C. residents. Participants must be 55-80 years of age, be a current smoker or former smoker, and have smoked for 20 years or more. To learn more about the BC Lung Screen Trial program, see BC Cancer – The BC Lung Screen Trial and BC Cancer – Lung.

Topic Overview

Screening tests help your doctor look for a problem before you have symptoms. This increases your chances of finding the problem early, when it's more treatable.

Studies don't show that routine screening for lung cancer is right for most people. But it may help those who have the highest risk for lung cancer—people 55 and older who are or were heavy smokers.

Lung cancer screening is done with a low-dose CT scan. A CT scan uses X-rays, or radiation, to make detailed pictures of your body.

Who should be screened for lung cancer?

Annual lung screening is only recommended for heavy smokers. That means people with a smoking history of at least 30 pack years. A pack year is a way to measure how heavy a smoker you are or were.

To figure out your pack years, multiply how many packs a day (assuming 20 cigarettes per pack) you smoke by how many years you have smoked. For example:

  • If you smoked 1 pack a day for 15 years, that's 1 times 15. So you have a smoking history of 15 pack years.
  • If you smoked 1½ packs a day for 20 years, that's 1.5 times 20. So you have a smoking history of 30 pack years.
  • If you smoked 2 packs a day for 15 years, that's 2 times 15. So you have a smoking history of 30 pack years.

Experts recommend annual lung cancer screening if:

  • You are 55 to 74 (some say 80) years old.
  • And you have a smoking history of at least 30 pack years.
  • And you still smoke, or you quit within the last 15 years.

Risks of lung cancer screening

CT screening for lung cancer isn't perfect. It can show an abnormal result when it turns out there was not any cancer. This is called a false-positive result. This means you may need more tests to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.

These tests may include more CT scans and invasive testing like a lung biopsy. In a biopsy, the doctor takes a sample of tissue from inside your lung so it can be looked at under a microscope. A biopsy is the only way to tell if you have lung cancer. If the biopsy finds cancer, you and your doctor will have to decide how or whether to treat it.

Some lung cancers found on CT scans are harmless and would not have caused a problem if they had not been found through screening. But because doctors can't tell which ones will turn out to be harmless, most will be treated. This means that you may get treatment—including surgery, radiation, or chemotherapy—that you don't need.

There is a small chance of getting cancer from being exposed to radiation. A low-dose CT scan uses more radiation than a regular chest X-ray. But it uses much less than a regular-dose CT scan. You and your doctor will decide if the possibility of finding lung cancer early is worth the risk of having this test and being exposed to the radiation.


Other Works Consulted

  • American Lung Association (2012). Providing Guidance on Lung Cancer Screening To Patients and Physicians. Accessed July 18, 2013.
  • Detterbeck FC, et al. (2013). Screening for lung cancer. Diagnosis and management of lung cancer, 3rd ed. American College of Chest Physicians evidence-based clinical practice guidelines. Chest, 143(5, Suppl): e78S–e92S.
  • U.S. Preventive Services Task Force (2013). Screening for lung cancer: U.S. Preventive Services Task Force Recommendation Statement. Annals of Internal Medicine. DOI:10.7326/M13-2771. Accessed January 9, 2014.
  • Wender R, Fontham ET, et al. (2013). American Cancer Society lung cancer screening guidelines. CA: A Cancer Journal for Clinicians, 63(2): 107–17.


Current as of:
April 29, 2020

Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Adam Husney MD - Family Medicine
Kathleen Romito MD - Family Medicine
Howard Schaff MD - Diagnostic Radiology