Position on Lung Cancer Screening

Lung Cancer Screening.


CATS acknowledges that the provision of clinical care, and the associated resources required to implement a potential lung cancer screening program are considerable, and ultimately may not be possible in each jurisdiction.

It is only within the confines of a dedicated lung cancer screening program, CATS recommends screening asymptomatic adults aged 55 to 74 years, who are in good health, with at least a 30 pack-year smoking history who smoke or have quit smoking within 15 years, with low-dose, non-contrast CT scanning of the chest, every year for three consecutive years. At this time CATS cannot provide a recommendation of subsequent screening following this 3-year interval

Discussion / Summary of the literature

The positions and recommendations herein should be regarded as the product of a non-systematic literature review. They are however in accordance (with some specific societal variations) with the positions advocated by the Canadian Task Force on Preventive Health Care, the US Preventive Services Task Force, the American College of Chest Physicians, The American Cancer Society, the American Association of Thoracic Surgery and the National Comprehensive Cancer Network. Our hope is that this recommendation is of utility to CATS members and other stakeholders including our patient community

  1. There is one large-scale, well powered RCT, several smaller RCTs and a number of institutional series to consider.
  2. The existing randomized trials produce conflicting conclusions regarding the benefit or absence of benefit to lung cancer screening.
  3. A large number of professional societies, task-forces and governing bodies have published formal position statements on lung cancer screening, and in particular the Canadian Task Force on Preventive Health has adopted a stance on this issue and is in favor of lung cancer screening.
  4. The primary study, which drives the general support in favor of lung cancer screening from most societies and task forces, is the National Lung Screening Trial (NLST)
  5. The NLST was a randomized trial comparing annual screening low-dose CT (LDCT) vs CXR for 3-years in >53,000 patients in the US. The study targeted “high-risk” patients with inclusion criteria being: i) men and women 55-74 years of age ii) history of at least 30 pack-years smoking (current or those who quit within 15 years of enrollment). The study had the following key findings:
      • A positive finding was that of a non-calcified nodule >4mm. 39% of LDCT screened patients had at least one positive scan
      • 4% of positive scans were false-positive scans, and follow up was at discretion of the institution
      • 90% of positive scans led to a further investigation
      • The rate of adverse events from interventions for positive scans was low at 1.4% of LDCT patients
      • There were 247 lung cancer deaths per 100,000 person-years in the LDCT group and 309 lung cancer deaths per 100,000 person-years in the CXR group
      • This translates into a relative reduction in lung cancer mortality of 20%, and a relative reduction in all-cause mortality of 6.7%
      • This translates to the need to screen 320 persons annually for 3-years to prevent one lung cancer death over six years
  6. There is some evidence that there may be benefit to screening patients at an earlier age or with fewer pack-year smoking history. This predominantly comes from the NELSON trial, which enrolled patients as young as 50 years of age and with 20 pack-year smoking history.
  7. CXR alone does not reduce mortality for lung cancer and is not recommended as a screening modality
  8. LDCT is more sensitive than CXR in detecting small asymptomatic lung cancers
  9. Screening has a high false positive rate, and leads to a large volume of additional investigations including further imaging and some invasive procedures
  10. Participation in a screen trial was associated with a favorable reduction in smoking cessation
  11. The concern of cost-effectiveness associated with screening is a major issue. Modelling studies suggest LDCT screening may reduce lung cancer mortality over 10 years at a cost of $81,0002 – 269,0003 per quality-adjusted life years.
  12. Screening for lung cancer cannot be thought of as a single intervention and requires a dedicated program that involves knowledgeable counselling, discussion of potential risks, expert radiology, thoracic surgery and pathology, and resources to ensure follow up and management of incidental findings
  13. Smoking cessation is a more effective and more cost-effective intervention to reduce lung cancer mortality than is screening

Recommended Reading

  1. Reduced lung-cancer mortality with low-dose computed tomography screening. NEJM. 2011;365(5):395.
  2. Cost-effectivenes of CT screening in the National Lung Screening Trial. NEJM 2014 Nov;371(19):1793-802
  3. Cost-effectiveness of computed tomography screening for lung cancer in the United States. J Thorac Oncol. 2011;6(11):1841.