Individual-Risk-Based Model to Select Smokers For CT Lung Cancer Screening May Prevent More Deaths

Among a group of U.S. ever-smokers age 50 to 80 years, application of an individual-risk-based model for computed tomography (CT) screening for lung cancer compared with selecting risk-factor-based subgroups for screening (such as current U.S. Preventive Services Task Force recommendations) was estimated to be associated with a greater number of lung cancer deaths prevented over 5 years, according to a study published online by JAMA. The study is being released to coincide with its presentation at the American Thoracic Society International Conference.
 
Lung cancer is the most common cause of cancer death in the United States. The U.S. Preventive Services Task Force (USPSTF) recommends CT lung cancer screening for ever-smokers age 55 to 80 years who have smoked at least 30 pack-years with no more than 15 years since quitting. Selecting individuals at highest lung cancer risk, as determined by individual risk calculations (i.e., risk-based selection) rather than by risk factor-based subgroups, might lead to more efficient screening. Risk-based selection more precisely delineates the benefits and harms of screening by accommodating detailed information on all lung cancer risk factors.
 
Hormuzd A. Katki, Ph.D., and Anil K. Chaturvedi, Ph.D., of the National Cancer Institute, Bethesda, Md., and colleagues conducted a comparison of modeled outcomes from risk-based CT lung-screening strategies vs USPSTF recommendations. The study included empirical risk models for lung cancer incidence and death in the absence of CT screening using data on ever-smokers from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO; 1993-2009) control group. Model validation in the chest radiography groups of the PLCO and the National Lung Screening Trial (NLST; 2002-2009), with additional validation of the death model in the National Health Interview Survey (NHIS; 1997-2001), a representative sample of the United States. Models were applied to U.S. ever-smokers age 50 to 80 years (NHIS 2010-2012) to estimate outcomes of risk-based selection for CT lung screening, assuming screening for all ever-smokers, and yield the percent changes in lung cancer detection and death observed in the NLST.
 
The researchers found that under USPSTF recommendations, the models estimated 9.0 million U.S. ever-smokers would qualify for lung cancer screening and 46,488 lung cancer deaths were estimated as screen-avertable over 5 years (estimated number needed to screen [NNS] to prevent 1 lung cancer death, 194). In contrast, risk-based selection screening of the same number of ever-smokers (9.0 million) at highest 5-year lung cancer risk was estimated to avert 20 percent more deaths (55,717) and was estimated to reduce the estimated NNS by 17 percent (NNS, 162).
 
“The key observation from the models is that compared with selecting risk-factor-based subgroups for screening (such as current USPSTF recommendations), individual-risk-based selection of smokers was estimated to prevent more deaths, improve screening effectiveness (defined as the NNS to prevent 1 lung cancer death), and improve screening efficiency (defined as the ratio of false-positive CT screening examinations to prevented deaths),” the authors write.
 
“Although CT screening can reduce lung cancer mortality by approximately 20 percent, the majority of lung cancer deaths are not screen-preventable at this time. The best way for smokers to avoid lung cancer, and all smoking-related illness, remains to quit smoking as early as possible.”
 
(doi:10.1001/jama.2016.6255; t