Lung Cancer Screening (PDQ®)–Health Professional Version

Overview

Separate PDQ summaries on Lung Cancer Prevention, Small Cell Lung Cancer Treatment, Non-Small Cell Lung Cancer Treatment, and Levels of Evidence for Cancer Screening and Prevention Studies are also available.

Evidence of Benefit Associated With Screening

Screening by low-dose helical computed tomography: benefit

One large randomized trial reported that screening persons aged 55 to 74 years who have cigarette smoking histories of 30 or more pack-years and who, if they are former smokers, have quit within the last 15 years reduces lung cancer mortality by 20% (95% confidence interval [CI], 6.8–26.7; P = .004) and all-cause mortality by 6.7% (95% CI, 1.2–13.6; P = .02).[1] An updated analysis showed that the estimated reduction in lung cancer mortality was 16% (95% CI, 5–25).[2]

Magnitude of Effect: 16% relative reduction in lung cancer–specific mortality.

Study Design: Evidence obtained from a randomized controlled trial (RCT).
Internal Validity: Good.
Consistency: Not applicable (N/A)—one randomized trial to date.
External Validity: Fair.

Screening by low-dose helical computed tomography: harms

Based on solid evidence, approximately 96% of all positive, low-dose helical computed tomography screening exams do not result in a lung cancer diagnosis.[1] False-positive exams may result in unnecessary invasive diagnostic procedures.

Magnitude of Effect: Based on the findings from a large randomized trial, the average false-positive rate per screening round was 23.3%. A total of 0.06% of all false-positive screening results led to a major complication after an invasive procedure performed as diagnostic follow-up to the positive screening result. Over three screening rounds, 1.8% of participants who did not have lung cancer had an invasive procedure following a positive screening result.

Study Design: Evidence obtained from an RCT.
Internal Validity: Good.
Consistency: Good.
External Validity: Fair.

Overdiagnosis

Based on fair evidence, some lung cancers detected by low-dose helical computed tomography screening appear to represent overdiagnosed cancer. The magnitude of overdiagnosis was 18% in one randomized trial and 67% in another randomized trial. These cancers result in unnecessary diagnostic procedures and also lead to unnecessary treatment. Harms of diagnostic procedures and treatment occur most frequently among long-term and/or heavy smokers because of smoking-associated comorbidities that increase risk propagation.

Magnitude of Effect: 18% to 67%, depending on characteristics of screened population and screening regimen.

Study Design: RCTs.
Internal Validity: Good.
Consistency: Fair.
External Validity: Fair.

Evidence of No Benefit Associated With Screening

Screening by chest x-ray and/or sputum cytology: benefits

Based on solid evidence, screening with chest x-ray and/or sputum cytology does not reduce mortality from lung cancer in the general population or in ever-smokers.

Magnitude of Effect: N/A.

Study Design: RCTs.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

Screening by chest x-ray and/or sputum cytology: harms

False-positive exams

Based on solid evidence, at least 95% of all positive chest x-ray screening exams do not result in a lung cancer diagnosis. False-positive exams result in unnecessary invasive diagnostic procedures.

Study Design: RCTs.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

Overdiagnosis

Based on solid evidence, a modest but non-negligible percentage of lung cancers detected by screening chest x-ray and/or sputum cytology appear to represent overdiagnosed cancer; the magnitude of overdiagnosis appears to be between 5% and 25%. These cancers result in unnecessary diagnostic procedures and also lead to unnecessary treatment. Harms of diagnostic procedures and treatment occur most frequently among long-term and/or heavy smokers because of smoking-associated comorbidities that increase risk propagation.

Magnitude of Effect: Between 5% and 25%, depending on characteristics of screened population and screening regimen.

Study Design: RCTs.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

References

Aberle DR, Adams AM, Berg CD, et al.: Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med 365 (5): 395-409, 2011. [PUBMED Abstract]
Pinsky PF, Church TR, Izmirlian G, et al.: The National Lung Screening Trial: results stratified by demographics, smoking history, and lung cancer histology. Cancer 119 (22): 3976-83, 2013. [PUBMED Abstract]

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Description of the Evidence