[Estimation of risk due to radiation exposure in the mass screening of cancer in Japan]

Abstract

Five types of mass screening programs for cancer are performed under the auspices of the Adult Health Promoting Act of the Japanese Government. The cancers involved are those of stomach, uterus, lung, breast and colon. Radiological images are routinely used for the screening of stomach and lung cancers, and mammography will be employed in the near future. In this study, the risk due to radiation exposure in the above-mentioned screening programs was estimated for an individual who participates in the screening of each cancer annually. The dose absorbed at each screening was estimated and an additive risk model was used as the pattern of occurrence of radiation-induced cancers for simplicity. Safety was also estimated. Results showed that the risk of a shortened life-expectancy as a result of undergoing annual mass screening for breast, stomach and lung cancer was insignificant in comparison with the average life-expectancy of about 80 years for Japanese men and women, and much smaller than the benefit of mass screening expressed in terms of prolonged life-expectancy. However, it should be emphasized that a quality control program must be established to keep the dose absorbed at each X-ray screening examination as low as reasonably possible.