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Higher risk thresholds for lung cancer screening may be more effective
Compared with current U.S. Preventive Services Task Force guidelines for lung cancer screening, new risk thresholds identified more current and former smokers eligible for screening and could potentially prevent more deaths, according study results recently published in Annals of Internal Medicine.
“Although lung cancer risk models have been validated, their risk thresholds are based on historical data,” Rebecca Landy, PhD, of the National Cancer Institute at the National Institutes of Health, and colleagues wrote. “Given large reductions in smoking over time, the current performance of these thresholds is unclear.”
The U.S. Preventive Task Force (USPSTF) lung cancer screening recommendations currently advise annual CT screening in current and former smokers, or ever-smokers, aged 55 to 80 years who had 30 or more pack-years of smoking who had quit smoking for no more than 15 years.
Researchers compared the USPSTF guidelines with three proposed risk thresholds. The first, recommended by the National Comprehensive Cancer Network (NCCN), would screen ever-smokers with a 6-year lung cancer risk of 1.3% or higher (1.3%-NCCN) based on the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial Model 2012 (PLCOM2012).
A second proposed risk threshold called for screening ever-smokers with a 6-year lung cancer risk of 1.51% or higher based on PLCOM2012 (1.51%- PLCOM2012).
The third proposed risk threshold recommended screening for those with a 5-year risk for lung cancer of at least 1.2% based on the Lung Cancer Death Risk Assessment Tool (LCDRAT; 1.2%-LCDRAT).
Researchers used data from the 2005 and 2015 National Health Interview Surveys (NHISs) to estimate the number of ever-smokers aged 50 to 80 years who were eligible for lung cancer screening based on the proposed risk thresholds. To estimate effectiveness, screening efficiency and false-positive screening results per prevented death (FPPDs), researchers used empirical modeling methods and statistical analyses.
In 2015, 8 million U.S. ever-smokers were eligible for screening based on USPSTF guidelines. The 1.3% or more NCCN risk threshold added 4.6 million (increase 57%; 95% CI, 49%-64%), 1.51% or more PLCOM2012 added 3.3 million (increase 41%; 95% CI, 34%-47%) and 1.2% or more LCDRAT added 1 million (increase 12%; 95% CI, CI, 5%-20%).
The results were a surprise to researchers because the 1.3% or higher NCCN threshold and the USPSTF guidelines selected the same proportion of ever-smokers in PLCO guidelines, and 1.51% or higher PLCOM2012 had a smaller proportion than both (35%). When applied to 2015 NHIS survey results, researchers found USPSTF guidelines selected a smaller proportion of ever-smokers (18%) than the 1.3% or higher NCCN (28%) and 1.51% or higher PLCOM2012 (25%) risk thresholds. The decreases in the proportion of ever-smokers identified for screening was due to significant changes in demographic characteristics and smoking histories from the time of PLCO enrollment from 1993 to 2001.
In 2005, the 1.3% or higher NCCN risk thresholds selected 12.7 million ever-smokers for screening, the 1.51% or higher PLCOM2012 selected 11.2 million and the USPSTF guidelines selected 8.7 million.
All three proposed risk thresholds could potentially prevent more deaths than current USPSTF screening guidelines.
Researchers noted that the 1.3% or higher NCCN and 1.51% or higher PLCOM2012 risk thresholds would screen millions more ever-smokers in the United States than the USPSTF guidelines but possibly with lower efficiency and more FPPDs.
“Risk thresholds should be reevaluated regularly as population characteristics change to ensure they maximize the number of deaths prevented with acceptable efficiency and minimal harms,” Landy and colleagues wrote. – by Erin Michael
Disclosures: Landy reports no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.