Abstract
ObjectivesTo portray the stage characteristics of lung cancers detected in CT screenings, and explore whether there’s universal stage superiority over other methods for various pathological types using available data worldwide in a meta-analysis approach.Materials and MethodsEMBASE and MEDLINE were searched for studies on lung cancer CT screening in natural populations through July 2015 without language or other filters. Twenty-four studies (8 trials and 16 cohorts) involving 1875 CT-detected lung cancer patients were enrolled and assessed by QUADAS-2. Pathology-confirmed stage information was carefully extracted by two reviewers. Stage I or limited stage proportions were pooled by random effect model with Freeman-Tukey double arcsine transformation.ResultsPooled stage I cancer proportion in CT screenings was 73.2% (95% confidence interval: 68.6%, 77.5%), with a significant rising trend (Ptrend<0.05) from baseline (64.7%) to ≥5 repeat rounds (87.1%). Relative to chest radiograph and usual care, the increased stage I proportions in CT were 12.2% (P>0.05), and 46.5% (P<0.05), respectively. Pathology-specifically, adenocarcinomas (66%) and squamous cell lung cancers (17%) composed the majority of CT-detected lung cancers, and had significantly higher stage I proportions relative to chest radiograph (bronchioloalveolar adenocarcinomas, 80.9% vs 51.4%; other adenocarcinomas, 58.8% vs 38.3%; squamous cell lung cancers, 52.3% vs 38.3%; all P<0.05). However, the percentage of small cell lung cancer was lower using CT than other detection routes, and no significant difference in limited stage proportion was observed (6.8% vs 10.8%, P>0.05).ConclusionCT screening can detect more early stage non-small cell lung cancers, but not all of them could be beneficial as there are a considerable number of indolent ones such as bronchioloalveolar adenocarcinomas. Still, current evidence is lacking regarding small cell lung cancers.
Highlights
With over one million annual fatal cases [1], lung cancer is incontestably the leading cancer burden worldwide
computed tomography (CT) screening can detect more early stage non-small cell lung cancers, but not all of them could be beneficial as there are a considerable number of indolent ones such as bronchioloalveolar adenocarcinomas
The National Lung Screening Trial (NLST) is the first and only randomized controlled trial (RCT) to date demonstrating that lung cancer mortality can be reduced by conducting computed tomography (CT) mass screening [15]
Summary
With over one million annual fatal cases [1], lung cancer is incontestably the leading cancer burden worldwide. An extensive number of studies focusing on the efficacy and feasibility of mass screening have been or are being conducted [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26] Among these efforts, the National Lung Screening Trial (NLST) is the first and only randomized controlled trial (RCT) to date demonstrating that lung cancer mortality can be reduced by conducting computed tomography (CT) mass screening [15]. Before balancing all of these benefits and potential adverse effects and before carrying out solutions to barriers in implementing a screening program [28], one fundamental key issue, namely the stage characteristics and stage superiority over other approaches of CT screen-detected cancers, has been raised but still not fully explored [20,29], which is the theoretical precondition of any screening benefits [30]
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