Lung cancer screening

Lung cancer screening with low-dose CT (LDCT) is an imaging strategy that is beginning to be adopted for high-risk patients in some health systems. Lung cancer is the most common cause of cancer death worldwide, and there is accumulating higher level evidence that a mortality benefit exists with screening of carefully selected patients.

A Lung-RADS screening classification exists for the purpose of standardizing follow up and management.

American Lung Association low dose CT lung cancer screening recommendations (based on National Lung Screening Trial criteria):

  • current or former smokers with at least a 30 pack-year history of smoking
  • 55-74 years of age
  • no history of lung cancer

Other recommendations:

  • smoking cessation must be emphasized for patients who are being screened 
  • imaging screening programs should be associated with multidisciplinary centers that can care for patients who need follow up
  • screening should not be mandatory, but the patient may choose it after a discussion of risks and benefits
  • detection of lung cancers at an early stage leads to better outcome (~52% 5 year mortality with stage I and 5% 5 year mortality at stage IV)
    • potential to decrease mortality
  • may have a positive effect in promoting smoking cessation (controversial)
  • a high false positive rate, requiring interventions, which has the potential to increase screening cost and morbidity on a population level
  • ionizing radiation from CT has the potential to increase radiation-induced cancer on a population level
  • possible "overdiagnosis" (the cancers found and treated may not effectively decrease the patient's mortality)
  • may have a negative effect in promoting smoking cessation (controversial)
  • randomized controlled trial 3
  • n = 53,454
  • 55-74 years of age
  • former or current smokers with over 30 pack year history
  • slightly healthier study cohort than U.S. population overall
  • three rounds of annual screening
  • positive if at least one noncalcified nodule >= 4 mm
  • nodules stable over three screening sessions considered benign
  • chest radiograph screening exam used as a control
  • low dose CT detected more nodules than radiograph, and greater than twice the diagnosis of stage IA
  • ~20% relative reduction in lung cancer mortality in the LDCT arm [95% CI, 6.8-26.7%]
  • absolute risk reduction in lung cancer death by 3-4:1000 individuals screened
  • ~6.7% reduction in all cause mortality [95% CI, 1.2-13.6%]
  •  Overall, 320 screened to save one life (mammography 1:465-601)

As with any screening program, the population-level benefits must be greater than the risks. There is increasing evidence that low dose lung cancer screening benefits outweigh the risks at this time for selected patient groups. There is continued debate over the cost effectiveness of screening, but it may be cost effective if limited to the study population or selected subgroups of the study population.

Further studies will refine lung cancer screening strategy, including a possible volume-based nodule assessment rather than single longest dimension assessment.

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Article information

rID: 32567
System: Chest
Synonyms or Alternate Spellings:
  • Low dose CT screening for lung cancer
  • CT screening for lung cancer

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