Original Article: Lung Cancer Screening: Pros and Cons [Lown Right Care]

Issue Date: June 15, 2019

Available at: https://www.aafp.org/afp/2019/0615/p740.html

To the Editor: As researchers studying lung cancer screening, we recognize the associated uncertainties. Dr. Leishman recently discussed lung cancer screening with more than 200 primary care clinicians and found that the concerns Drs. Lazris and Roth raised in their article are shared by many frontline clinicians. However, reports from recently completed European lung cancer screening trials affirm the benefit of screening. The current strategy used for interpreting nodules on lung cancer screening examinations (American College of Radiology Lung Imaging Reporting and Data System) is more conservative than the strategy used in the National Lung Screening Trial and may significantly reduce false-positive rates compared with the National Lung Screening Trial. Weighing the balance of benefit and harm is challenging, especially for individual patients whose lung cancer risk and general health may not reflect that of the average trial participant.

Although clinicians have reservations about the generalizability of the National Lung Screening Trial, almost all acknowledge that the evidence cannot be totally discounted, and most feel some obligation to offer screening. We have often heard these clinicians say things like, “I've been meaning to get around to lung cancer screening.” Most acknowledge that screening might be a good idea for some patients, saying things like, “if a patient is a very heavy smoker with a very high lung cancer risk but no major health issues, then I might recommend screening.” There is an important insight embedded in this line of thinking: some patients can likely expect a much larger than average benefit from lung cancer screening.

How can clinicians identify patients who are more likely to benefit from lung cancer screening? If an eligible patient is reasonably healthy, clinicians could consider calculating individualized lung cancer risk using one of several well-validated risk models.¹ We and others have developed web-based tools to help clinicians incorporate individualized risk calculations into decision-making.² Individualized risk assessment can be helpful because patients at higher risk of developing lung cancer are also more likely to benefit from early detection through screening.³ When lung cancer risk increases, uncertainty about whether to recommend screening decreases when the person has a reasonable life expectancy.⁴

At a time when screening uptake is so low (i.e., 2% to 6% of eligible patients get screened),⁵ making an effort to identify patients at high risk who are in otherwise good health for whom screening is likely to be highly advantageous might be an idea that primary care clinicians can agree on.

In Reply: We appreciate the response to our article. The authors state correctly that recent European studies confirm the benefit of the National Lung Screening Trial, with similar survival benefits of three to six people out of 1,000 screened avoiding lung cancer death over five to 10 years of screening. However, doubt about the net benefit of lung cancer screening persists, which may be why few doctors are implementing lung cancer screening.

False-positive rates for low-dose computed tomography scans are high. In the German Lung Cancer Screening Intervention Trial, women inexplicably had a survival advantage with screening, but men did not; it is possible that other ongoing studies will continue to introduce uncertainty about who benefits and who does not. In older studies, the survival rate is not significant, and those studies need to be factored into our knowledge base.¹ There are still many questions left unanswered, especially as to who benefits the most from screening (e.g., active vs. distant smokers, high pack-year history vs. lower pack-year) and whether we can reduce the risk of false-positive screenings without compromising the benefit of screening.

The use of web-based methods to identify high-risk patients who may benefit from lung cancer screening seems potentially valuable and may, after being verified, help reduce unnecessary screenings while enhancing the benefit to risk ratio of screening. Until then, we hope our article provides physicians and patients with sufficient information about the risks and benefits of screening to help them make a shared decision.