USPSTF approach to lung cancer screening may not be most effective strategy

The U.S. Preventive Services Task Force criteria for lung cancer screening often misses patients who are good candidates for screening and is not the most cost-effective strategy, while risk-targeted low-dose CT testing is more effective in preventing lung cancer deaths, but is modest in terms of life-years saved, quality-adjusted life-years and cost-effectiveness, according to two studies published in Annals of Internal Medicine.

“The [USPSTF] recommends annual low-dose CT lung cancer screening for persons aged 55 to 80 years who currently smoke or quit within the past 15 years and have at least a 30–pack-year history of cigarette smoking… These 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,” Li C. Cheung, PhD, from the National Cancer Institute, and colleagues wrote.

Cheung and colleagues used data from the 2005 (n = 5,460), 2010 (n = 5,155) and 2015 (n = 6,971) nationally representative National Health Interview Survey to determine the effect of USPSTF screening eligibility on deaths from lung cancer preventable by screening, compared with individualized, risk-based eligibility. Participants included ever-smokers aged between 50 to 80 years who did not report having lung cancer.

The researchers used the Lung Cancer Risk Assessment Tool and Lung Cancer Death Risk Assessment Tool to estimate the individual 5-year risks for lung cancer incidence and mortality. They also used USPSTF criteria to estimate the number of smokers in the United States who were eligible and ineligible for screening.

Between 2005 and 2010, the number of ever-smokers eligible for screening increased from 8.7 million to 9.5 million. However, this number decreased to 8 million between 2010 and 2015. Based on reaching risk threshold criteria, screening eligibility decreased by only 0.8 million from 2010 to 2015, half of the decrease based on USPSTF criteria.

Additionally, 2,617 more deaths from lung cancer could have been prevented over 5 years using individual risk-based criteria rather than the USPSTF criteria in 2005 and 5,115 more deaths in 2015. The researchers noted that since smoking prevalence and intensity decreased significantly between 2010 and 2015 among the United States population, following the USPSTF criteria resulted in fewer screening-eligible ever-smokers and preventable lung cancer deaths by screening.

“To better capture high-risk smokers and prevent premature deaths from lung cancer, eligibility for lung cancer screening should be based on reaching a cost-effective risk threshold that balances CT screening benefits and harms by using a lung cancer risk tool validated in the U.S. population,” Cheung and colleagues concluded. “The gap in screening effectiveness between risk-based and USPSTF screening criteria may continue to increase in the future.”

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In a separate study, Vaibhav Kumar, MD, from Tufts Medical Center, and colleagues sought to determine the cost-effectiveness of lung cancer screening based on risk-targeted selection compared with the National Lung Screening Trial (NLST) eligibility criteria using a multistate prediction model. They noted that the USPSTF guidelines for lung cancer screening are largely based on the NLST eligibility criteria.

During the initial 7 years, there were 1.2 lung cancer deaths prevented per 10,000 person-years for participants in the lowest decile and 9.5 deaths prevented for those in the highest decile. However, lung cancer mortality benefits were not substantial in regard to life-years (extreme decile ratio, 3.6) and QALYs (extreme decile ratio, 2.4) across risk groups.

The researchers found that participants who were older and had more comorbidities and higher screening-related costs were at an increased risk for lung cancer death. These higher-risk individuals have a shorter life expectancy, lower quality of life and require more invasive tests; thus, the risk-targeted based approach resulted in fewer QALYs and higher costs for such patients, according to the researchers.

Incremental cost-effectiveness ratios ranged from $75,000 per QALY in the lowest risk decile to $53,000 per QALY in the highest risk decile.

These findings were not substantially different in sensitivity analyses.

“Although risk targeting may improve screening efficiency in terms of early lung cancer mortality per person screened, the gains in efficiency are attenuated and modest in terms of life-years, QALYs, and cost-effectiveness,” Kumar and colleagues concluded.

In a related editorial, Angela K. Green, MD, MSc, and Peter Bach, MD, MAPP, both from the Memorial Sloan Kettering Cancer Center, wrote that these data confirm that low-dose CT screening can improve lung cancer mortality rates.

“Although risk-based identification of persons who should be offered screening is empirically superior to using the current cutoffs, the more pressing concern is why people, regardless of how their eligibility is defined, are not receiving the test,” they wrote. – by Alaina Tedesco

References:

Cheung LC, et al. Ann Intern Med. 2017;doi:10.7326/M17-2067.

Green AK, Bach P. Ann Intern Med. 2017;doi:10.7326/M17-3316.

Kumar V, et al. Ann Intern Med. 2017;doi:10.7326/M17-1401.

Disclosure: Cheung, Kumar and Green report no relevant financial disclosures. Please see studies and editorial for all other authors’ relevant financial disclosures.