Overdiagnosis in lung cancer: different perspectives, definitions, implications

Does lung cancer screening lead to overdiagnosis? Most lung cancer prevention experts think it does, but there is a contingent who believe that it does not. This latter group holds fast to a notion that essentially all histological foci of lung cancer pose an imminent threat to health, irrespective of how they are discovered. Enter Dr Reich’s interesting and thoughtful article,1 which provides a cohesive overview of the epidemiological data that would be explained by “overdiagnosis”, and therefore the case for its existence (see page 377). Reich also considers the totality of studies that are oft cited as evidence that “overdiagnosis” does not exist. For these articles, he summarises their findings too, and raises his concerns about them. It is an important contribution, that clearly presents Reich’s view that overdiagnosis is a serious concern in lung cancer screening. Because it also incorporates opposing evidence, it is a worthy reference for anyone interested in understanding this confusing issue.

My interpretation of the data is much like Reich’s—I have little doubt that lung cancer screening, particularly with CT, uncovers vast numbers of lesions with relatively little malignant potential. I also harbour little doubt that surgical treatment of individuals who are overdiagnosed is potentially very harmful to them, given that surgery confers risks both short and long term. However, as a clinician, I find this epidemiologic concept hard to operationalise because current knowledge does not allow me to distinguish between those histological foci that pose a reduced threat compared with those that pose a very real and imminent threat. Therefore, faced with a positive biopsy at this point, it is essentially an instinctual response to recommend immediate and definitive treatment.

Perhaps this tension between epidemiological data and clinical instinct is what leads to different interpretations of the available data. This …