Lung cancer screening: screening frequency and lung cancer risk

Lung cancer is the commonest cause of cancer death worldwide. Along with primary prevention such as tobacco control, screening with low-dose computed tomography (LDCT) has the potential to reduce lung cancer mortality. Screening has already been implemented in some countries but national health authorities in many countries have yet to adopt lung cancer screening as a public health policy. Although there is evidence to support the effectiveness of LDCT screening in high-risk groups there are many challenges to implementing a cost-effective lung cancer screening program and there are still unanswered questions about how to most efficiently select high risk groups for screening, how to optimally manage lung nodules and how frequently to offer screening. A recent retrospective cohort analysis of data from the National Lung Screening Trial (NLST) provides some evidence to support the concept that annual screening might not be necessary for all participants in a lung cancer screening program. Individuals with a negative baseline LDCT result have been shown to have a lower incidence of lung cancer and reduced lung cancer mortality at follow up compared with all participants in baseline screening and the relative costs, benefits and harms of annual screening in this group may differ compared to those with a positive prevalence LDCT. Further research is needed to determine whether risk prediction models incorporating the findings of prevalence LDCT scans can be used to guide the frequency of subsequent screening in order to maximize the efficient use of resources and reduce the harms associated with screening.