Lung Cancer Screening: Radiology's Opportunity Here and Now

Abstract

David Gur, ScD More than 30 years ago when the Breast Cancer Detection Demonstration Project was performed in a large number of institutions as a “field trial,” it was considered virtually a revolutionary concept (1). Many associated scientific and operational issues that needed to be addressed were unknown at the time. Despite valid concerns regarding the uncertainties of potential benefits, radiation risk, the ability to maintain participants’ compliance, and the potential cost associated with periodic screening for early detection of breast cancer, the program was, in retrospect, one of the primary successful steps in a long series of events that led to the recommendation for annual mammographic screening. Although several similar issues are still being raised 30 years later, the fact is that screening for early detection of breast cancer has become but one factor in the great success we are beginning to observe; namely, a noticeable reduction in mortality associated with this disease (2–4). It took more than 20 years and numerous changes in our practices to come to this point. It is becoming clearer by the year that whatever we are doing collectively through better detection, intervention, and management it seems to be working. The controversy associated with mass screening for early detection of breast cancer, and the manner in which this controversy was addressed, should serve as an important lesson. When considering screening for early detection of lung cancer, we should be able to learn from the processes undertaken in breast cancer screening and not have to repeat at least some of these steps before exhibiting strong support toward the initiation of such a program—at a minimum as a large field trial in a high-risk population. Lung cancer is a major public health concern that contributes substantially to morbidity and mortality, especially in the smoking and past-smoker populations. Computed tomography (CT) is a very effective tool in depicting nodules (masses) associated with most types of lung cancer, and the majority of studies that have attempted to assess the possible benefits of CT-based cancer screening found the expected increase in detection during the initial examination (the “prevalence” or “baseline” screening examination) (5). The average size of a cancer detected through this type of intervention, in particular during repeat screening (second examination and beyond), is smaller than that detected (frequently as an incidental finding) in the nonscreened population (6,7). There are several aspects of screening for early detection of lung cancer that we can, for the most part, agree on—perhaps not in terms of absolute values but rather on a relative scale. First, while imaging-based lung cancer screening may not be the optimal solution for all types of lung cancers, we can agree that in most instances “smaller” at detection generally means “earlier” and, on average, also means detection at a lower stage. Because, on average, detection at a lower stage leads to a better outcome, this should be considered a strong point in favor of some type of screening if we can demonstrate that specific practices will actually result in earlier detection. Many physicians believe that the imaging modality of choice for earlier detection should be thin-section low-dose CT (8–10). I am of the belief that there are ample data from case-control and population-based studies that support a statement that welland meticulously performed screening with posteroanterior chest radiography will also result in earlier detection, albeit probably not as early as with CT examinations (11,12). Second, unfortunately, modeling the potential benefits (and risks) of lung Published online 10.1148/radiol.2382050706