Years-smoked criteria may improve lung cancer screening eligibility

Using total years smoked as a lung cancer screening criterion may better identify patients likely to benefit from low-dose CT screening, according to research published June 29 in JAMA Internal Medicine. 

Smoke duration thresholds are simple to apply and can identify more people who may benefit from lung cancer screening, wrote a team led by Lauren Kearney, MD, from the VA Boston Healthcare System in Massachusetts. However, the researchers cautioned that trade-offs between efficiency and population reach should be carefully weighed. 

“Decision makers must weigh these trade-offs according to priorities such as resource availability and the imperative to avoid missing those who may gain the most,” Kearney and colleagues wrote. 

Emerging evidence suggests total years smoked may better capture risk than current guidelines that use pack-years and years since cessation. However, the researchers noted uncertainty about the best years-smoked threshold for screening. 

The Kearney team studied a nationally representative sample to evaluate performance and trade-offs of years-smoked lung cancer screening criteria. It used the Life-Years from Screening–Computed Tomography (LYS-CT) model to estimate projected gains in life expectancy from screening based on individual lung cancer risk and baseline life expectancy. 

The cohort study analyzed 2024 National Health Interview Survey data from more than 57 million adults aged 40 to 80 who had ever smoked. Researchers compared screening criteria from the U.S. Preventive Services Task Force (USPSTF) screening criteria against three alternative years-smoked thresholds: 40 or more years, 30 or more years, and 20 or more years. The USPSTF criteria require age 50 to 80, at least 20 pack-years of smoking, and current smoking or cessation within the past 15 years. 

The study expands on earlier cohort-based work by quantifying the population-level impact of years-smoked criteria in a nationally representative sample, offering policymakers new data as screening guideline discussions continue. 

The results showed that all three years-smoked criteria outperformed the USPSTF guidelines in capturing individuals expected to gain the most from screening. The USPSTF criteria identified 77% of highest-benefit individuals, while the 40-or-more-years threshold captured 85%, the 30-year threshold captured 97%, and the 20-year threshold captured 99%. 

However, the thresholds differed sharply in how efficiently they screened and in how many low-benefit individuals they pulled in. The 40-year threshold was the most precise, excluding all lowest-benefit individuals and identifying the smallest eligible population at roughly 10 million people, slightly fewer than the 11.4 million captured under USPSTF criteria.  

The 20-year threshold, meanwhile, tripled the screened population to more than 32 million while including a large proportion of individuals with the least expected benefit. 

The 30-year threshold emerged as a potential middle ground, capturing nearly all highest-benefit individuals and still excluding 96% of lowest-benefit individuals, while expanding eligibility to roughly 20 million people. 

The authors noted that the right threshold will depend heavily on healthcare system priorities. A more stringent cutoff like 40 years may suit systems with limited screening capacity, while a 30-year threshold could broaden access with only modest efficiency losses, they suggested. 

“Criteria should be implemented with individualized risk assessment, decision support, and capacity planning to balance benefits, harms, and feasibility,” the authors wrote. 

Read the full study here.