Date Published: February 7, 2018
Publisher: Public Library of Science
Author(s): Steven D. Criss, Deirdre F. Sheehan, Lauren Palazzo, Chung Yin Kong, Steven D. Shapiro
Abstract: BackgroundPrevious simulation studies estimating the impacts of lung cancer screening have ignored the changes in smoking prevalence over time in the United States. Our primary rationale was to perform, to our knowledge, the first simulation study that estimates the health outcomes of lung cancer screening with explicit modeling of smoking trends for the whole US population.Methods/FindingsUtilizing a well-validated microsimulation model, we estimated the benefits and harms of an annual low-dose computed tomography screening scenario with a realistic screening adherence rate versus a no-screening scenario for the US population from 2016–2030. The Centers for Medicare and Medicaid Services (CMS) eligibility criteria were applied: age 55–77 years at time of screening, history of at least 30 pack-years of smoking, and current smoker or former smoker with fewer than 15 years since quitting. In the screened population, cumulative mortality reduction was projected to reach 16.98% (95% CI 16.90%–17.07%). Cumulative mortality reduction was estimated to be 3.52% (95% CI 3.50%–3.53%) for the overall study population, with annual mortality reduction peaking at 4.38% (95% CI 4.36%–4.41%) in 2021 and falling to 3.53% (95% CI 3.50%–3.56%) by 2030. Lung cancer screening would save a projected 148,484 life-years (95% CI 147,429–149,540) across the total population through 2030. There were estimated to be 9,054 (95% CI 9,011–9,098) overdiagnosed cases among the 252,429 (95% CI 251,208–253,649) screen-detected lung cancer diagnoses, yielding an overdiagnosis rate of 3.59%. The limitations of our study are that we do not explicitly model race or socioeconomic status and our model was calibrated to data from studies performed in academic centers, both of which may impact the generalizability of our results. We also exclusively model the effects of the CMS guidelines for lung cancer screening and not any other screening strategies.ConclusionsThe mortality reduction and life-years gained estimated by this study are lower than those of single birth cohort studies. Single cohort studies neglect the changing dynamics of smoking behavior across generations, whereas this study reflects the trend of decreasing smoking prevalence since the 1960s. Maximum benefit could be derived from lung cancer screening through 2021; in later years, mortality reduction due to screening will decline. If a comprehensive screening program is not implemented in the near future, the opportunity to achieve these benefits will have passed.
Partial Text: Despite more than 50 years having passed since the publication of the first Surgeon General’s Report on Smoking and Health and the expansive tobacco control efforts that have followed, lung cancer is still the leading cause of cancer-related deaths in the US [1,2]. This suggests that additional lung cancer control policies are necessary to work alongside tobacco control and cessation efforts in order to effectively reduce lung cancer deaths . For example, lung cancer screening with low-dose computed tomography (CT) has been shown to improve early detection of lung cancer and reduce mortality among screened individuals [4,5]. The National Lung Screening Trial (NLST) resulted in a 20.0% reduction in lung cancer mortality for individuals at high risk of developing lung cancer when screened with low-dose CT compared to those screened with chest radiography . The US Preventive Services Task Force (USPSTF) subsequently released a recommendation supporting low-dose CT screening , requiring private insurers to cover the cost of screening . In 2015, the US Centers for Medicare and Medicaid Services (CMS) also issued a coverage determination for annual lung cancer screening with low-dose CT .
Using the LCPM, we performed, to our knowledge, the first multiple birth cohort simulation study to estimate the health outcomes of lung cancer screening for the whole US population. Over the period 2016–2030, our model estimated that the number of people eligible for screening would decrease from 11,773,243 (95% CI 11,767,138–11,779,347) to 6,836,326 (95% CI 6,830,837–6,841,815). During this period, cumulative lung cancer mortality reduction was estimated to be 3.52% and 16.98% for the total population and screened individuals, respectively. The estimated lung cancer mortality reduction within the screened population was similar to the observed result of 20.0% in the NLST. Our study predicts that lung cancer screening at a population level would yield 14.50 overdiagnosed cases for every 100 deaths avoided and 3.59 overdiagnosed cases for every 100 cases of screen-detected lung cancer. We used a screening adherence rate of 45% in our base case scenario in order to provide realistic estimates of the benefit of a fully implemented lung cancer screening program. Compared to the results using an ideal adherence rate of 100%, the more practical rate used in our study demonstrates how improving the adherence rate is pivotal to the success of a population-level screening program.