Mass Screening by Indirect Method

Abstract

In Japan, lung cancer screening using chest X-ray and sputum cytology has been conducted for 18 years since 1987. Although it is retrospective, the efficacy of lung cancer screening in terms of lung cancer mortality reduction has been evaluated by several case-control studies, such as those conducted in Miyagi, Niigata and Okayama Prefectures, and positive results have been reported. Therefore, if it is implemented properly, its effect should be observed in national statistics. However, age-adjusted incidence and mortality for lung cancer have been showing almost parallel trends so far, which means effectiveness of lung cancer screening has not been observed at the national level. On the other hand, in Miyagi, Niigata and Okayama Prefectures the magnitude of decrease in lung cancer mortality seemed to be greater than the national average, which suggested high-quality screening had been conducted with higher participation rate in these areas. In other areas, no apparent effects can be expected by continuing current activities, and fundamental discussion of the problem is needed.