2012 EDUCATIONAL BOOK - American Society of Clinical Oncology

LUNG CANCER SCREENING
Fig. 2. Guidelines published by the National Comprehensive Cancer Network for the diagnostic evaluation of positive screens in which
non-solid (ground glass) nodules are detected. Abbreviations: LDCT, low-dose helical computed tomography. Reproduced with permission from
the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines for Lung Cancer Screening V.1.2012). © 2012 National Comprehensive
Cancer Network, Inc. All rights reserved. The NCCN Guidelines and illustrations herein may not be reproduced in any form for any purpose
without the express written permission of the NCCN. To view the most recent and complete version of the NCCN Guidelines, go online to
NCCN.org. NATIONAL COMPREHENSIVE CANCER NETWORK ® , NCCN ® , NCCN GUIDELINES ® , and all other NCCN Content are trademarks owned
by the National Comprehensive Cancer Network, Inc.
Opportunities
There are major opportunities to be gained in the process
of screening implementation. The NLST successfully addressed
the critical endpoint of differential lung cancer
mortality, and secondary analyses will inform the costeffectiveness
of LDCT in older, heavy smokers. However,
broad-scale implementation of LDCT screening is predicated
on several variables that the NLST does not directly address
and for which further research is crucial. Among these are
considerations of the optimal risk profile of those who are
screened, and how risk profiles might be used to guide
diagnostic strategies.
Morphologic features of indeterminate lung nodules on
CT have been studied as potential predictors of lung cancer.
Most analyses have relied on subjective visual assessment
of nodule features such as: size (diameter), consistency
(ground glass, part-solid, or solid), border definition, and
internal features, such as reticulation, air bronchograms
and bubble-like lucencies. 37 Quantitative analysis of lung
nodules using CAD seeks to characterize nodules by math-
ematical feature descriptors. We are at the cusp of validating
analytic software that can reproducibly characterize
lung nodules across a range of nodule types. 38,39 Such
nodule characterization could become standard in the diagnostic
stratification of individuals with indeterminate nodules.
Between 80% and 90% of lung cancers occur in tobacco
smokers, yet only 10% to 15% of chronic smokers develop
lung cancer. Prospective studies have also shown that approximately
25% of smokers develop COPD as defined by
spirometry, whereas 50% to 80% of patients with lung
cancer have COPD. 40,41 Relative to smokers with normal
lung function, those with COPD have up to a six-fold
increased risk of lung cancer, making COPD by far the
greatest risk factor for lung cancer in ever smokers. 41 These
observations suggest an inherently greater risk of lung
cancer among smokers with COPD than smokers with
normal lung function. Although COPD and lung cancer have
in common smoking exposure, several lines of evidence now
support underlying shared genetic susceptibility that acts in
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