Lung cancer screening with low-dose computed tomography after the National Lung Screening Trial. The debate is still open

Abstract

The aim of this article is to highlight some concerns regarding lung cancer screening with CT through a thorough analysis of scientific literature. The publication of the National Lung Screening Trial in 2011 has revealed that CT screening of smokers and ex-smokers in three annual rounds reduces lung cancer mortality a 20% when compared with thorax x-ray screening. The first limitation of this screening modality is its lack of downstaging in successive screening rounds compared with the initial round. Also, lung cancer screening with CT has a low positive predictive value, similar to the percentage of unnecessary surgeries performed in false positives. Another problem is that, at present, the burden of lung cancer overdiagnosis is not known. It is to be expected that if overdiagnosis occurs when thorax x-ray screening is used it will be greater when using CT. CT, even at low doses, exposes patients to high levels of radiation. Dealing with positive nodules entails an even higher radiation dose and the number of cancer cases induced by radiation in patients screened with CT is not known. Lastly, published studies on lung cancer CT screening are vastly heterogeneous. They include different age groups, different types of smokers and ex-smokers and different tomogram thickness, making the results hardly comparable. In this context we do not recommend lung cancer screening with CT for smokers or ex-smokers outside of the context of individual counseling.