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Guidelines & Advice
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Ontario Lung Screening Program Frequently Asked Questions for Healthcare Providers

Find answers to frequently asked questions about the importance of organized lung cancer screening and the Ontario Lung Screening Program on this page.

To find lung cancer screening resources, including those for radiologists, see Lung Cancer Screening Information for Healthcare Providers.

Why is lung cancer screening for people at high risk needed in Ontario?

Lung cancer is a leading cause of cancer death for people in Ontario. In 2020, approximately 7,100 people were expected to die from lung cancer in Ontario. That is more than the number of people who were expected to die of breast, colon and prostate cancers combined.

Survival for people in Ontario who have been diagnosed with lung cancer has improved, rising from 17.8% (2002 to 2006) to 24.4% (2012 to 2016). However, lung cancer survival continues to be much lower than survival for breast (88.5%), colon (68.6%) and prostate (93.1%) cancers.

The reason so many people die from lung cancer is that by the time it is usually diagnosed, the cancer has spread to other parts of the body or is too big. When the cancer has spread or is too big, treatment has less of a chance of working.

Now we have an effective and evidence-based way to screen people so that we can find some lung cancers early, when treatment has a better chance of working.

 

 

What is a low-dose computed tomography (LDCT) scan?

People who are at high risk of getting lung cancer and are eligible to get screened will be offered a special type of computed tomography (CT) scan that uses a small amount of radiation. This test is called a “low-dose CT scan.”

During an LDCT scan, the screening participant lies on an open table that passes through a large donut-shaped machine called a “scanner.” The scanner uses a small amount of radiation to take detailed pictures of the lungs. The test only takes a few minutes and is not painful. There are no medications or needles given during the test.

Why is low-dose computed tomography (LDCT) used for lung cancer screening for people at high risk of getting lung cancer?

Ontario Health (Cancer Care Ontario) recommends using LDCT through an organized cancer screening program to screen people at high risk of getting lung cancer. We based this recommendation on evidence from the National Institute of Health’s National Lung Screening Trial, a randomized controlled trial with over 50,000 participants. The trial showed that people at high risk of getting lung cancer who got screened with 1 LDCT scan annually over approximately 2 years (1 scan shortly after randomization and 2 follow-up scans) had a 20% relative reduction in lung cancer mortality over 6 years, compared with people who got screened the same number of times at the same interval with chest X-ray. Because of its randomized controlled trial design, this study provides strong evidence for the efficacy of screening.

Screening with LDCT can find lung cancer at an early stage, when treatment has a better chance of working. The amount of radiation someone is exposed to through an LDCT for lung cancer screening is:

Therefore, LDCT minimizes the potential harms of screening for people who are otherwise healthy.

People who participate in screening may have many scans over time, so it is important to keep their radiation dose as low as possible. Although the lower dose of radiation in an LDCT scan produces less detailed images than a diagnostic CT, LDCT is good at finding small lung nodules. However, a diagnostic quality CT and/or other tests are needed to accurately diagnose and stage lung cancer.

What are the potential benefits and risks of screening people at high risk of getting lung cancer with low-dose computed tomography (LDCT)?

The benefit of screening with LDCT is that it reduces the chance of dying from lung cancer because it can find lung cancer at an early stage when treatment has better chance of working.

The potential risks of screening with LDCT include:

  • false-positive results (i.e., when someone has an abnormal LDCT screening result, even though they do not have cancer)
  • over-diagnosis (i.e., identifying a cancer that would not have caused someone harm if they had not been screened)
  • harms from radiation exposure and other procedures that may be needed

 

Will the Ontario Lung Screening Program be expanded?

The Ontario Lung Screening Program is currently happening at 4 site hospitals. We are planning to add more Ontario Lung Screening Program site hospitals across the province in the future.

How does the Ontario Lung Screening Program determine eligibility?

A screening navigator from the Ontario Lung Screening Program site hospital will determine a person’s eligibility for screening through a risk assessment. The risk assessment is done using a risk calculator, which is based on a statistical risk prediction model that gives an estimate of someone’s risk (as a percentage) of developing lung cancer in the next 6 years. The risk assessment considers factors such as:

  • age
  • cigarette smoking history
  • body mass index
  • education
  • personal history of cancer and chronic obstructive pulmonary disease
  • family history of lung cancer

People with a 2% or greater risk of developing lung cancer over the next 6 years are considered eligible to participate in the Ontario Lung Screening Program.

Someone is not eligible to participate in the Ontario Lung Screening Program if they:

  • have been diagnosed with lung cancer
  • are under surveillance for lung nodules
  • have had hemoptysis of unknown cause or unexplained weight loss of more than 5 kilograms in the past year
  • are currently undergoing diagnostic assessment, treatment or surveillance for life-threatening conditions (such as a cancer with a poor prognosis) as assessed by the referring healthcare provider

Why does the eligibility for the Ontario Lung Screening Program differ from the National Lung Screening Trial (NLST)?

The risk assessment to determine eligibility for the Ontario Lung Screening Program is done using a risk calculator, which is based on a statistical risk prediction model that gives an estimate of someone’s risk (as a percentage) of developing lung cancer in the next 6 years.

The risk calculator is used to determine eligibility for lung cancer screening in the Ontario Lung Screening Program because its risk prediction model has been demonstrated to be more sensitive and have a higher positive predictive value than the criteria used to determine eligibility in the National Lung Screening Trial, which was based on age, pack-years (number of packs of cigarettes someone smoked per day multiplied by the number of years they smoked) and the time since someone stopped smoking. By using a more sensitive risk prediction model to choose participants, the Ontario Lung Screening Program identifies people who are most likely to develop lung cancer and who are therefore most likely to benefit from lung cancer screening.

 

What should healthcare providers do if they have patients who may be eligible for screening, but are not located near an Ontario Lung Screening Program site hospital?

Healthcare providers can refer individuals who live outside of an Ontario Lung Screening Program hospital site’s catchment area. If the referral is accepted, the healthcare provider must work with the Ontario Lung Screening Program site hospital to make sure appropriate diagnostic follow-up is organized.

We encourage all healthcare providers to discuss smoking cessation with their patients. People who stop smoking greatly reduce their risk of disease and early death. Smoking cessation services can help reduce the morbidity and mortality for lung cancer, other cancers and chronic diseases associated with smoking, such as stroke and coronary heart disease.

What should radiologists from hospitals not participating in the Ontario Lung Screening Program do if they get a requisition for a computed tomography (CT) scan for lung cancer screening?

These are the key considerations for radiologists who get a requisition for a computed tomography (CT) scan for lung cancer screening:

  • Whether the benefits would outweigh the potential harms of the scan
  • Ontario Health (Cancer Care Ontario) recommends using low-dose computed tomography to screen people at high risk of getting lung cancer through an organized cancer screening program.
  • Screening people at an official Ontario Lung Screening Program site hospital provides several benefits of an organized cancer screening program, such as:
    • screening appropriate people at the recommended interval
    • appropriate and timely follow-up of abnormal findings
    • ongoing quality monitoring, reporting and performance management
  • Screening is not appropriate for people with suspected lung cancer. If someone has lung cancer symptoms, follow the Program in Evidence Based Care’s guidelines for referral of suspected lung cancer and the Ontario Health (Cancer Care Ontario) lung cancer diagnosis pathway.

How should a healthcare provider manage a patient with lung nodules identified on an opportunistic screening computed tomography (CT) scan?

If someone has already had a CT scan for screening outside of the Ontario Lung Screening Program, their healthcare provider may follow the recommendation provided by the radiologist on the radiology report.

The radiologist’s recommendation for follow-up should be based on an established system for managing nodules.

If there is no clear recommendation on the radiology report, the healthcare provider should contact the reporting radiologist to determine appropriate follow-up.

What was the Lung Cancer Screening Pilot for People at High Risk?

Previously, lung cancer screening was available in Ontario through the Lung Cancer Screening Pilot for People at High Risk (the pilot), which ended in March 2021. The hospitals that participated in the pilot are now part of the Ontario Lung Screening Program. We plan to add more Ontario Lung Screening Program hospital sites across the province in the future.

For more information on the pilot and to access pilot resources, send us an email.

References

  1. Ontario Health (Cancer Care Ontario). Ontario Cancer Statistics 2020. Toronto: Ontario Health (Cancer Care Ontario); 2020
  2. Cancer System Quality Index [Internet]. Toronto (ON). Cancer survival [2020; cited 2021 Apr]. Available from: https://www.csqi.on.ca/en/2020/indicators/cancer-survival
  3. Roberts H, Walker-Dilks C, Sivjee K, Ung Y, Yasufuku K, Hey A, et al. Screening High-Risk Populations for Lung Cancer: Guideline Recommendations. J Thorac Oncol [Internet]. 2013 Oct;8(10):1232–7. Available from: https://www.sciencedirect.com/science/article/pii/S1556086415330148?via%3Dihub
  4. Aberle D, Adams A, Berg C, Black W, Clapp J, Fagerstrom R, et al. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med. 2011 Aug;365(5):395–409.
  5. Radiologyinfo.org [Internet]. Radiological Society of North America, Inc.; c2021. Radiation dose in X-ray and CT exams [reviewed 2019 Mar; cited 2021 Apr]. Available from: http://www.radiologyinfo.org/en/info.cfm?pg=safety-xray
  6. Canadian Nuclear Safety Commission [Internet]. Government of Canada. Natural background radiation [modified 2020 Nov; cited 2020 May]. Available from: : http://nuclearsafety.gc.ca/eng/resources/fact-sheets/natural-background-radiation.cfm
  7. Tammemagi MC, Katki HA, Hocking WG, Church TR, Caporaso N, Kvale PA, et al. Selection criteria for lung-cancer screening. N Engl J Med. 2013 Feb;368(8):728–36.