Possible overdiagnosis of early-stage lung adenocarcinoma among never-smokers in Taiwan

Abstract

Extract Overdiagnosis in cancer screening denotes the detection of cancer that does not cause premature mortality [1, 2]. A standard approach to estimate the magnitude of overdiagnosis is through randomised controlled trials and comparing the cancer incidence in the screened group with that in the control group [3]. Recent studies from Asian countries showed that the promotion of computed tomography (CT) screening among individuals who mostly never smoked was associated with a rapidly increased incidence of early-stage lung cancer, whereas a corresponding declined incidence of advanced lung cancer was not observed [4–6]. However, not all of these early-stage cancers were overdiagnosed. Notably, participants with completely resected stage IA lung cancer in the National Lung Screening Trial had a 5-year cumulative incidence of recurrence of 16%, and 81% of the recurrences were distant metastases [7]. As a tumour size of >1 cm is a significant predictive factor of growth in non-solid lung nodules [8], we hypothesised that adenocarcinoma in situ (AIS), bronchioloalveolar carcinoma (BAC) and minimally invasive adenocarcinoma (MIA) with tumour sizes >1 cm are unlikely to be overdiagnosed. We attempted to corroborate our hypothesis by comparing the survival of never-smoking patients with that of matched referents.