From the Guidelines
Low-dose computed tomography (LDCT) scan is the recommended initial imaging test for lung cancer screening in eligible smokers, not chest X-ray. This recommendation is based on evidence showing that LDCT screening can reduce lung cancer mortality by approximately 20% compared to chest X-ray screening, as demonstrated in the National Lung Screening Trial (NLST) 1. The most recent and highest quality study, published in 2018, supports this recommendation, suggesting that annual screening with low-dose CT should be offered to asymptomatic smokers and former smokers age 55 to 77 who have smoked 30 pack years or more and either continue to smoke or have quit within the past 15 years 1.
Key Points
- LDCT is more sensitive than chest X-ray for detecting small lung nodules and early-stage lung cancers when treatment is most effective.
- While chest X-rays are less expensive and involve lower radiation exposure, they frequently miss early-stage lung cancers.
- The radiation dose from LDCT is significantly lower than conventional CT scans, making it appropriate for screening purposes.
- Patients should discuss their individual risk factors with their healthcare provider to determine if they meet the criteria for lung cancer screening, as the benefits of early detection must be weighed against potential harms such as false positives, incidental findings, and cumulative radiation exposure.
Recommendations
- LDCT is recommended annually for adults aged 50-80 who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years.
- Clinicians with access to high-volume, high-quality lung cancer screening and treatment centers should initiate a discussion about lung cancer screening with patients who meet the eligibility criteria.
- Screening should not be viewed as an alternative to smoking cessation, and patients should be informed of their continuing risk of lung cancer and offered cessation treatments.
From the Research
Guidelines for Smokers
The guidelines for smokers regarding chest X-ray (CXR) or low-dose computed tomography (LDCT) scan for lung cancer screening are as follows:
- The National Lung Screening Trial (NLST) demonstrated a 20% reduction in lung cancer mortality for screening with low-dose computed tomography versus chest radiography 2.
- Current guidelines suggest that eligible adults with a heavy smoking history will benefit from annual low-dose computed tomography (LDCT) but due to several associated risks, a shared decision-making consultation is required 3.
- LDCT was positive in 24.2% of screens, compared with 6.9% of CXRs; more than 95% of all positive LDCT screens were not associated with lung cancer 4.
- Lung cancer-specific mortality was reduced by 20% relative to CXR; all-cause mortality was reduced by 6.7% 4.
Recommended Imaging
The recommended initial imaging for lung cancer screening in smokers is:
- Low-dose computed tomography (LDCT) for adult patients 55 to 80 years of age who have a 30 pack-year smoking history and currently smoke or have quit within the last 15 years 5.
- LDCT is preferred over CXR due to its higher detection rate of early-stage lung cancers and lower mortality rate 2, 4.
Key Considerations
Key considerations for lung cancer screening in smokers include:
- The balance between the benefits and harms of screening, including false-positives, radiation exposure, and overdiagnosis 2, 3, 4.
- The importance of shared decision-making consultations to discuss the risks and benefits of screening 3.
- The need for further research to determine the appropriate risk cohorts for screening and to improve diagnostic prediction of lung cancer in the setting of screen-detected nodules 2, 4.