Methods: Since June 2015, more than 6000 LDCT were done at the NTUHCT. Roughly 6 months after the test telephone follow-ups about patient satisfactions, self-awareness of CT results, medical consultations and other related behaviors, and willingness of coming back for another test were routinely done. Retrospective secondary data analysis will be performed on the telephone follow-up results to establish local epidemiology data on lung pathology as well as information on screening accuracy of LDCT. Customers are also queried about willingness to provide their medical records, and linkage to National Health Insurance Database with informed consents to provide more advanced information on their long-term outcomes.