Avoiding overdiagnosis in lung cancer screening: the volume doubling time strategy

Abstract

It has been 2 years since the breakthrough publication of the National Lung Cancer Screening Trial (NLST) results, yet there are still unresolved questions about cancer screening. Despite the possibility of reducing lung cancer-related mortality, the risk of detecting indolent lesions that are not life threatening, especially in advanced-age patients, still exists. Another problem is the number of false-positive findings leading to unnecessary diagnostic work-ups. In the NSLT study, for example, 27.2% of computed tomography participants were false positives, leading to follow-up diagnostic procedures in 90% of cases and to surgery in 4.2% [1]. Of course, computed tomography protocols and criteria for screening positivity should ensure accurate detection of all potentially malignant lesions, but this goal alone is not sufficient. Ideally, screening protocols should allow us to detect only true lung cancers, leaving out benign lesions, and among the malignant lesions detected, we should only be identifying those that are sufficiently aggressive to be potentially life threatening. This issue of the European Respiratory Journal includes two articles addressing precisely these problems. The paper by Infante et al. [2] is a review article dedicated to the slow-growing lung cancer entity, whereas the paper from Horeweg et al. [3] gives an overview of the NELSON strategy’s performance, especially its rate of false positives. Infante et al . [2] provide evidence of slow-growing lung cancers by analysing tumour volume doubling times (VDTs) in different lung cancer series. Considering a VDT >400 days to define slow-growing lung cancers, they report a highly variable proportion, ranging from 3% in the International Early Lung Cancer Action Program (I-ELCAP) [4] to 45% in some Japanese series [5]. The authors emphasise that only a minority of baseline VDTs were assessed in I-ELCAP, but …