Repeat lung cancer screenings reveal less CXR abnormalities with different variations than first-time screening

Objectives: Chest radiography (CXR) is the most common screening procedure for the detection of lung cancer. A comparative CXR review can help to detect new shadows. Participants (pts) who undergo repeated screening at the same facility as the health check-up can receive a comparative review of the CXR. It has been hypothesized that the diagnosis of CXR abnormalities in screening would be different when compared to previous CXR and when not. Methods: We retrospectively analyzed one-year cohort derived from the ongoing MedCity21 health check-up registry. The pts with abnormalities requiring medication in CXR were invited to our clinic for chest computed tomography (CT). We compared the varieties of abnormalities on CXR between repeated and first-visit pts using chi-square tests. Results: A total of 13,690 repeated / first visits of 7872 / 5818 (57.5 / 42.5%) pts were enrolled. The CXR abnormalities included 324 of 143 / 191 pts and 234 of 108 / 126 pts who underwent chest CT, respectively. Repeated pts had a significantly lower proportion of abnormalities in CXR that required medication than the first-visit pts (p < 0.01). CT confirmation revealed that CXR abnormalities in repeated pts were diagnosed with different variations compared to those of first-visit pts. Repeated pts had a significantly lower proportion of old inflammatory changes (p=0.02) and a higher proportion of acute inflammatory shadow (p=0.02) than first-visit pts. Conclusions: Immediate confirmation by CT revealed that CXR abnormalities in repeated pts were diagnosed with different variations compared to those of firsttime pts. A comparative review of previous CXR may be highly effective in ruling out lung cancer. *Correspondence to: Tatsuo Kimura, M.D. Ph.D., Department of Premier Preventive Medicine, Graduate School of Medicine, Osaka City University, 1-143 AbenoHARUKAS 21F, Abenosuji, Abeno-ku Osaka 545-6090, Japan, Tel: 81-6-6624-4041; Fax: 81-6-6624-8212; E-mail: kimutats@med.osaka-cu.ac.jp