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Vol.39 No.6 contents | Japanese/English |
- Original Article -
Mathematical Simulation of Mortality Reduction in Mass Screening of Lung Cancer with Special Emphasis on Helical CT (LSCT) Screening
Takeshi IinumaDepartment of Engineering, Saitama Institute of Technology
Objective: To estimate mortality reduction of lung cancer by mass screening using chest X-rays and helical CT. Methods: A deterministic model of cancer screening was employed to calculate the number of deaths (A) due to lung cancer in the screened population and those (B) in the unscreened population (background risk) and then derive the relative risk (RR) by calculating A/B and risk difference (RD) by calculating (B-A). Three types of mass screening were evaluated: (1) mass screening with indirect chest X-rays, (2) mass screening with direct chest X-rays and (3) mass screening with helical CT. Results: The calculated RR was 0.90 with 95% confidence interval (0.66-1.23) for screening with indirect X-rays, 0.82 (0.60-1.13) for that with direct X-rays and 0.46 (0.31-0.67) for that with helical CT in a 100,000 population with an incidence of 100/100,000 person-years compared to the same population without screening. The 95% CI of RR shows that screening with the two types of chest X-rays is not effective in reducing mortality, since the upper bound of RR exceeds 1.0. However, screening with helical CT may significantly reduce the mortality of lung cancer, since the upper bound of RR is well below 1.0. Conclusion: Introduction of lung cancer screening with helical CT should be considered for secondary prevention of lung cancer instead of the present method of chest X-ray radiographs.
key words: Mortality reduction, Mass screening, Chest X-rays, Helical CT, Relative risk
Received: April 5, 1999
Accepted: July 23, 1999
JJLC 39 (6): 805-812, 1999
