a populationbased cohort study to evaluate the effectiveness of lung cancer screening using lowdose ct in hitachi city japan objectives to evaluate the effectiveness of lung cancer screening using lowdose computed tomography for the general population we conducted a retrospective cohort study of screening for participants among hitachi residentsmaterials and methods citizens aged 5074 who underwent lowdose computed tomography screening at least once during 19982006 were defined as the computed tomography group and those who underwent xray screening at least once during the same period but did not receive lowdose computed tomography screening throughout the followup period were defined as the xp group we investigated the lung cancer incidence rate mortality rate and allcause mortality rate for both groups from the first lung cancer screening to the end of 2012results in the computed tomography group 17 935 residents 9790 males and 8145 females 273 cases of lung cancer 15 72 cases of lung cancer death 04 and 885 cases of allcause death 49 were observed on the other hand 164 cases 11 of lung cancer 80 cases 05 of lung cancer death and 1188 cases 76 of allcause death were observed in the xp group 15 548 residents 6526 males and 9022 females the hazard ratios of the computed tomography group to the xp group adjusted for gender age and smoking history were 123 for lung cancer incidence rate 049 for lung cancer mortality rate and 057 for allcause mortality rate nonsmokers and light smokers 30 packyears had a significantly lower lung cancer mortality 041 and 021 respectivelyconclusion lowdose computed tomography screening for a population including nonsmokers and light smokers may be effective