“…The screening population has a prevalence of cancer that is much lower than a clinic-based population, in which physicians are often requested to characterize larger, incidentally discovered SPNs. As a matter of fact the Brock model was developed from 7008 nodules of which only 102 were cancers (1.45 %) [19], whereas reported prevalence of malignancy in a clinic-based population ranges typically between 23 % and 58 % [5,7,8,18]. For this reason we believe that this kind of model should not be taken into account for comparison when dealing with SPNs detected in clinical practice.…”