More Eligible Individuals for Risk-Based Approach to Lung Cancer Screening

January 4, 2018

An individual risk–based approach could identify more people eligible for lung cancer screening, and thus prevent more early deaths, compared with USPSTF criteria.

An individual risk–based approach could identify more people eligible for lung cancer screening, and thus prevent more early deaths, compared with the US Preventive Services Task Force (USPSTF) screening criteria, according to a new analysis. A second study, however, found that risk-based screening may not be any more cost-effective or efficient in terms of life-years gained.

The USPSTF low-dose CT screening criteria targets individuals aged 55 to 80 years who currently smoke or who quit within the last 15 years and who have at least a 30–pack-year history of smoking. Between 2010 and 2015, the number of people who met those criteria dropped sharply. “However, those criteria may exclude smokers at high risk for lung cancer who would have been selected for CT screening by individual risk calculators that more specifically account for demographic, clinical, and smoking characteristics,” wrote study authors led by Li C. Cheung, PhD, of the National Cancer Institute in Bethesda, Maryland.

Researchers used data from the National Health Interview Survey to compare USPSTF criteria and a risk-based approach (using the Lung Cancer Risk Assessment Tool) to screening eligibility. The study included 5,460 individuals from 2005, 5,155 from 2010, and 6,971 from 2015; all those included were ever-smokers aged 50 to 80 years without self-reported lung cancer; results were then extrapolated out to estimate eligibility for the entire United States. The results were published in Annals of Internal Medicine.

Using USPSTF eligibility criteria, the number of individuals eligible for screening rose from 8.7 million in 2005 (24.6% of ever-smokers aged 50 to 80 years) to 9.5 million in 2010 (22.8%). The number then dropped substantially, to 8.0 million in 2015 (18.4%). That decrease was markedly less using a risk-based approach: the number of smokers with a 5-year lung cancer risk of at least 2.0% decreased by 0.8 million from 2010 to 2015, about half that seen with USPSTF guidelines (P = .048).

Similarly, the decrease in deaths averted due to screening was attenuated using the risk-based approach. Between 2010 and 2015, USPSTF criteria showed a decrease in deaths averted of 6.4% (8,122 fewer deaths averted); using a risk-based approach of 5-year lung cancer risk of 2.0%, the drop was 3.2%. In 2005, using a 5-year risk of 2.5% instead of USPSTF criteria would have prevented 2,617 more lung cancer deaths, while in 2015 the difference grew to 5,115 deaths.

Though the total number of individuals eligible for screening based on USPSTF guidelines decreased by 1.5 million from 2010 to 2015, there was an increase of 1.3 million people who had a 20– to 29–pack-year history of smoking. “These smokers may have had sufficiently high individual risk for lung cancer to be eligible for screening by risk-based criteria,” the authors wrote.

Though the benefits of risk-based screening seem clear based on that study, another study, also published in Annals of Internal Medicine, showed that there are caveats. It found that though risk-based screening may improve efficiency in terms of early lung cancer mortality per person screened, those gains are lessened when life-years, quality-adjusted life-years, and cost-effectiveness are considered.