The study has been carried out using data from different sources by applying mathematical models. It does not add value to what has already been published on known risk factors. 

The quality of the analysis could be improved, as it finally only uses three predictor variables (age, duration of smoking and packs per year). These factors seem insufficient to determine risk, as both gender and socio-economic status should be taken into account to determine and advise individualised screening. 

The work is in line with the evidence (clinical trials), although it does not provide new evidence to those published (NELSON, NLST, PLCO). On the other hand, the authors compare studies of different populations, which may represent a study design bias. The mathematical models are difficult to interpret with my knowledge of the field, as biostatisticians and bioinformaticians are needed to assess the adjustments made and the validation of the models. 

Although the authors present it as a predictive tool, its applicability at a practical level (health professionals) is debatable in the case of indicating a person for screening (low-dose CT). It should be adjusted to be a tool to help both professionals and patients (Framingham study of cardiovascular risk). Biomarkers, environmental, occupational factors should be considered.