Patient-Oriented Evidence That Matters

Screening Smokers for Lung Cancer with Low-Dose CT Decreases Lung Cancer Mortality


Am Fam Physician. 2021 May 15;103(10):630.

Clinical Question

Does low-dose computed tomography (CT) screening for lung cancer prevent mortality in smokers?

Bottom Line

High-quality trials show that low-dose CT screening decreased lung cancer mortality in smokers. (Level of Evidence = 1a)


A systematic review of nine randomized trials that screened smokers for lung cancer using low-dose CT was summarized in another POEM by Essential Evidence. The authors of the current study used references from a systematic review (published in 2019) and conducted a supplemental search of PubMed. They only included randomized trials at low risk of bias (based on the Cochrane Risk of Bias tool) and identified the same nine randomized trials. One was deemed to be at high risk of bias, leaving eight studies with 90,475 participants. The eight studies enrolled people with 20 to 30 or more pack-years of smoking and who ranged from 45 to 75 years of age. The median follow-up ranged from 5.2 years to 10 years, and the lung cancer mortality rate varied from 1.6% to 4.6%. After pooling the results, people screened with low-dose CT were less likely to die from lung cancer (relative risk = 0.81; 95% CI, 0.74 to 0.89; number needed to treat = 250). Although all-cause mortality was slightly lower in the screened group, this was not statistically significant (relative risk = 0.96; 95% CI, 0.92 to 1.01). The mortality data were fairly homogeneous across studies. Other than identifying an overdiagnosis rate of approximately 20%, the authors do not report on the harms of screening.

Study design: Meta-analysis (randomized controlled trials)

Funding source: Unknown/not stated

Setting: Various (meta-analysis)

Reference: Ebell MH, Bentivegna M, Hulme C. Cancer-specific mortality, all-cause mortality, and overdiagnosis in lung cancer screening trials: a meta-analysis. Ann Fam Med. 2020;18(6):545–552.

POEMs (patient-oriented evidence that matters) are provided by Essential Evidence Plus, a point-of-care clinical decision support system published by Wiley-Blackwell. For more information, see http://www.essentialevidenceplus.com. Copyright Wiley-Blackwell. Used with permission.

For definitions of levels of evidence used in POEMs, see http://www.essentialevidenceplus.com/product/ebm_loe.cfm?show=oxford.

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This series is coordinated by Sumi Sexton, MD, editor-in-chief.

A collection of POEMs published in AFP is available at https://www.aafp.org/afp/poems.



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