Dr Simpson1 makes a compelling argument as to why, for the overwhelming majority of patients who do not meet the current criteria for lung cancer screening with chest CT scan, such scans should not be ordered. There is no evidence whatsoever that screening chest CT scans benefit patients who are not at high risk according to current guidelines. Dr Simpson makes the additional important point that the evidence base continues to evolve, and that following publication of ongoing and future trials, we may need to revisit whether even high-risk patients derive benefit, on average, from lung cancer screening. However, even if recommendations evolved such that there was no patient group for whom screening CT scans were recommended, one still could not conclude with certainty that no individual patient might benefit from such screening. Indeed, it is mathematically impossible to prove that screening cannot benefit a group of patients, let alone an individual patient.