Summary of Evidence

Screening for Lung Cancer With Chest X-Ray and/or Sputum Cytology
        Benefits
        Harms
Screening for Lung Cancer With Low-Dose Helical Computed Tomography (LDCT)
        Benefits
        Harms

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.

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

Description of the Evidence

• Study Design: Evidence obtained from randomized controlled trials.
• Internal Validity: Good.
• Consistency: Good.
• Direction and Magnitude of Effect: No evidence of effect.
• External Validity: Good.

Based on solid evidence, screening would lead to false-positive tests and unnecessary invasive diagnostic procedures and treatments. Also, screening would lead to diagnosis of cancers that would never have been identified without screening (overdiagnosis), which also would lead to harms. Harms of diagnostic procedures and therapy may be more frequent among long-term/heavy smokers because of comorbidities.

Description of the Evidence

• Study Design: Evidence obtained from randomized controlled trials.
• Internal Validity: Good.
• Consistency: Good.
• Direction and Magnitude of Effect: False-positive results range from 4% to 15%; there is a possibility of overdiagnosis and overtreatment (magnitude uncertain).
• External Validity: Good.

There is evidence 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% and all-cause mortality by 6.7%.

Description of the Evidence

• Study Design: Evidence obtained from a randomized controlled trial.
• Internal Validity: Good.
• Consistency: Not applicable—one randomized trial to date.
• Direction and Magnitude of Effect: 20% relative reduction in lung cancer–specific mortality.
• External Validity: Fair.

Based on solid evidence, screening would lead to false-positive tests in approximately one-quarter of those screened. Most abnormalities would be monitored radiographically. However, persons with false-positive screened and overdiagnosed cancers would be exposed to unnecessary invasive diagnostic procedures and treatments. Furthermore, harms of invasive diagnostic procedures and therapy may be more frequent among the heaviest smokers and those who have smoked for long periods of time because of comorbidities.

Description of the Evidence

• Study Design: Evidence obtained from a randomized controlled trial.
• Internal Validity: Good.
• Consistency: Good.
• Direction and Magnitude of Effect: Positive. Magnitude is a 20% relative reduction in lung cancer–specific mortality and a 6.7% reduction in overall mortality.
• External Validity: Fair.