Lung Cancer Screening Eligible?
Authors: Joseph Yeboah
Journal: Circulation (2018)

◼ primary prevention ◼ risk factors I n 2015, the Centers for Medicare and Medicaid services published a decision memorandum to pay for annual low-dose computer tomography (LDCT) of the chest for lung cancer screening (LCS) in individuals 55 to 77 years of age with no signs or symptoms of lung cancer who are (1) current smokers, (2) former smokers but quit in the last 15 years, and (3) have a tobacco smoking history of ≥30 pack years. 1 This publication was followed by the US Preventive Services Task Force recommendation of LDCT in smokers who met the Centers for Medicare and Medicaid services criteria but are 55 to 80 years of age. 2 The LCS recommendation was based largely on the results of the NLST (National Lung Screening Trial), 3 which showed a significant reduction in mortality in the LDCT arm compared with the chest radiography arm.The NLST also showed that atherosclerotic cardiovascular disease (ASCVD) was the most common cause of death in the trial.Thus, strategies aimed at the reduction of ASCVD risk in the lung cancer screening-eligible population (≈9 million annually in the United States) have the potential of reducing mortality even more than that which may be obtained from the early screening for lung cancer.Identification of individuals at risk for future ASCVD in the general population is based on tools such as the pooled cohort equation, the modified Framingham risk score, and nontraditional cardiovascular risk markers.Among the nontraditional risk markers, computer tomography assessment of the coronary artery calcium (CAC) score has shown the most promise and has even been incorporated in current guidelines for primary prevention of ASCVD. 4 A qualitative or semiquantitative assessment of CAC can also be reported from the LDCT scan performed for lung cancer screening at no additional cost.Limited data exist on the performance of the pooled cohort equation or the Framingham risk score plus or minus CAC in this unique population with high observed ASCVD risk.Findings from the limited data on this important subject (Table ) suggest that the pooled cohort equation/Framingham risk score has poor discriminative ability in this population, and CAC has a limited role, unlike that observed in the general population. 5The actual ASCVD event rate of LCS-eligible individuals appears well above the 7.5% and 10% thresholds for statin eligibility recommended by the 2013 American College of Cardiology/American Heart Association cholesterol guidelines and US Preventive Services Task Force guidelines, respectively.In addition, the observed event rate of the LCS-eligible individuals is also well above the threshold for the initiation of antihypertensive medication therapy among individuals with stage 1 hypertension according to the 2017 American College of Cardiology/American Heart Association hypertension guidelines.In this paradigm, methods for upward risk reclassification that identify those with the highest risk among this already high-risk group (LCS eligible) for primary prevention therapies would have minimal to no value.In contrast, downward reclassification would be of more potential value, but even downward classification using the absence of CAC is inadequate for derisking this unique population for primary prevention of Downloaded from http://ahajournals.org by on August 20, 2023