Lung cancer incidence in middle-aged men estimated by low-dose computed tomography screening

Abstract

Lung cancer incidence in general middle-aged men estimated by low-dose computed tomography screening has been unknown. We conducted a longitudinal study to estimate the incidence of lung cancer in general middle-aged Japanese men based on smoking status and to determine the optimal targets for lung cancer screening. The subjects were 14,058 Japanese men aged 40–59 years (mean age, 48.3 years; median age, 49 years) who underwent twice or more low-dose computed tomography screenings at Nippon Telegraph and Telephone East Corporation Izu Hospital at the baseline examination during 2000–2007. Medical records of subjects with abnormal findings were collected and analyzed. The lung cancer incidence in men aged 40–59 or 50–59 years based on smoking status by person-years method, and relative risks of current- and former-smokers compared with non-smokers were calculated. Mean follow-up period was approximately 3 years, and total person-years were 45,152. The incidence was 24.4 per 100,000 person-years in men aged 40–59 years (95% confidence interval (95% CI) 13.6–43.6), and 56.5 in men aged 50–59 (95% CI 31.6–101). No statistically significances were observed among non-, current- and former-smokers. However, the relative risk of the current-smokers aged 50–59 years with 40 or more pack-years, compared with non-smokers was 6.31 (95% CI 1.27–31.3), and was statistically significant. No significant differences in the lung cancer incidence existed among any smoking status in the Japanese men aged 40–59 years. In this population, men aged 50–59 years with 40 and more pack-years could be an optimal target for lung cancer screening. The small number of incident lung cancers resulting in the incidence and relative risks with the wide 95% CI and the participants’ demographic biases were the limitations of our study. Our screening recommendations should be made with more caution.