OBJECTIVES: Lung cancer is a heavy burden worldwide and screening program should be expected. We reevaluated the effectiveness of CXR screening and compared the histology distribution for the target population for lung cancer screening between the US and Japan.

METHODS: We performed a systematic review and meta-analysis for CXR screening for lung cancer. The study design included RCT, cohort, and case-control studies that evaluated the efficacy/effectiveness of CXR screening. Literature searches were conducted using PubMed, Cochran Library, Web of Science, and Ichushu-web until April 2022. Backgrounds of evaluation studies were compared between Japan and other countries.

RESULTS: From over 3000 articles as a candidate, six RCT, one cohort, and six case-control studies were selected. Five RCTs were conducted from the 1960s to 1970s, except for the PLCO. All RCTs suggested there was no reduction in lung cancer by CXR screening. Six case-controlled studies in Japan reported mortality reduction from lung cancer. The meta-analysis results showed a 43% mortality reduction from lung cancer (Adjusted odds ratio 0.53, 95%CI: 0.50-0.63). Although the subjects of RCT were limited to men except for the PLCO and KFS, the Japanese studies included women as 20% of the case groups. Histological distribution of lung cancer was similar in the period when the PLCO and Japanese CCS were performed. During that period, squamous cell carcinoma decreased according to a decrease in the smoking rate, but adenocarcinoma has increased, particularly in Asian women. Although CXR was used for lung cancer screening, the target disease differed between old RCTs and Japanese CCS. The PLCO is a contemporary study, and the results reflected the same background as the Japanese studies. However, the dilution effect might affect the PLCO results because of extended follow-up beyond the lead time.

CONCLUSIONS: Although evidence of CXR screening is limited, it might be adopted in Japan considering background risk.