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Coronary Artery Calcium Detected on Lung Cancer Screening CT and All-Cause Mortality: The National Lung Screening Trial

Principal Investigator
Name
Janet Snell-Bergeon
Degrees
PhD; MPH
Institution
University of Colorado Health Science Center
Position Title
Assistant Professor
Email
About this CDAS Project
Study
NLST (Learn more about this study)
Project ID
200912-0013
Initial CDAS Request Approval
Dec 8, 2009
Title
Coronary Artery Calcium Detected on Lung Cancer Screening CT and All-Cause Mortality: The National Lung Screening Trial
Summary
Coronary artery disease (CAD) remains the leading cause of death among adults in the United States . Smoking is a well recognized risk factor for CAD, and is also the cause of most deaths from chronic obstructive pulmonary disease (COPD) and nearly one third of cancers. Measurement of coronary artery calcium (CAC) using multi-detector CT has emerged as a useful tool for CAD risk stratification, adding incremental knowledge to known CAD risk factors such as dyslipidemia, hypertension, and smoking. Low dose spiral CT is being evaluated in large clinical trials for screening of lung cancer, and CAC is a common incidental finding on CT for lung cancer screening. Among high risk individuals such as older adults with substantial smoking exposure, the detection of CAC on low dose ungated CT may provide important information regarding the risk for mortality. In the National Lung Screening Trial (NLST), serial low dose CT scans have been performed on over 25,000 adults with at least 30 pack-years of smoking exposure. We are proposing to quantify CAC on 17,000 of these scans from the NLST baseline exam and a randomly selected subset of scans from the two-year follow-up exam (T2), and examine the prediction of all-cause mortality by baseline CAC and change in CAC over two years.
Aims

People who are at risk for lung cancer due to a history of heavy smoking are also at increased risk for coronary artery disease (CAD). The utility of low-dose CT for the purpose of lung cancer screening is currently under study. Coronary artery calcium (CAC), a surrogate marker for atherosclerotic plaque burden, can also be quantified from low-dose ungated CT. The presence and extent of CAC has been shown to strongly predict all-cause and CAD mortality. The ability to detect increased risk for CAD during low-dose CT lung cancer screening may provide important additional value to screening CT in these patients. Therefore, we aim to quantify coronary artery calcium in the low-dose gated screening CT scans which have been collected as part of the National Lung Screening Trial in order to: Specific Aim 1: Examine whether the assessment of coronary artery calcium (CAC) measured by low-dose CT improves prediction of all-cause mortality. Hypothesis 1a: All-cause mortality will be increased in study subjects who have CAC at baseline, even after adjusting for current smoking and pack-years of smoking. Hypothesis 2a: All-cause mortality will increase with the severity of CAC score, and CAC extent will provide additional incremental information regarding mortality risk beyond other established risk factors (history of diabetes, heart disease, increasing age, male sex, current smoking and pack-years of smoking). Specific Aim 2: Determine whether serial measurements of CAC add to the prediction of all-cause mortality Hypothesis 2a: Progression of CAC over two years of follow-up will predict increased risk of all-cause mortality Hypothesis 2b: The measurement of serial CAC scores will add incremental information regarding all-cause mortality risk independent of the extent of CAC present at the baseline examination

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