Assessment of Lung Cancer Risk Among Smokers for Whom Annual Screening Is Not Recommended

Area of Science:

• Pulmonology
• Oncology
• Epidemiology

Background:

• The US Preventive Services Task Force (USPSTF) guidelines do not recommend annual low-dose computed tomography (LDCT) screening for lung cancer in certain adult groups.
• These groups include former smokers with 20+ pack-years who quit over 15 years ago, and current smokers with less than 20 pack-years.
• This exclusion criteria leaves a significant population at risk for undiagnosed lung cancer.

Purpose of the Study:

• To determine the incidence and risk of lung cancer in older adults who fall outside the current USPSTF low-dose computed tomography (LDCT) screening recommendations.
• To identify specific subgroups within this population who may benefit from further risk stratification or screening.
• To inform the development of improved lung cancer screening strategies for underserved populations.

Main Methods:

• A cohort study utilizing data from the Cardiovascular Health Study (CHS), including 4279 participants aged 65 and older with baseline smoking history.
• Participants were categorized based on smoking status (current, former, never) and pack-year history, with follow-up for incident lung cancer.
• Statistical analysis employed Fine-Gray subdistribution hazard models and Cox cause-specific hazard regression to estimate lung cancer incidence and hazard ratios (HRs) compared to never smokers.

Main Results:

• Incident lung cancer occurred in 5.0% of current smokers with less than 20 pack-years and 5.0% of former smokers with 20+ pack-years who quit 15+ years ago.
• Compared to never smokers, the cause-specific hazard ratios for lung cancer were significantly elevated: 10.54 (95% CI, 3.60-30.83) for current non-heavy smokers and 11.19 (95% CI, 5.40-23.21) for former smokers with extended cessation.
• Age, sex, and race-adjusted HRs remained high, indicating a substantial risk in these populations.

Conclusions:

• Smokers who do not meet current criteria for low-dose computed tomography (LDCT) lung cancer screening exhibit a high risk of developing lung cancer.
• There is a critical need for advanced prediction models to identify high-risk individuals within these non-recommended groups.
• The findings support the re-evaluation of current screening guidelines to potentially include these at-risk populations.