Abstract
We examined clinical stage distribution and proportion of screen-detected cases of stomach, colorectal, lung, female breast and cervical cancer by sex and age group using Osaka Cancer Registry data from 2000-2014. The proportion of local or in situ stage cancer had increased for all age groups in all sites, except stomach cancer in the 0-49 years group and female breast cancer in the 80 years and older group. The proportion of screen-detected cases had increased during the study period for all age groups in all cancer sites. While the proportion increased noticeably in the younger groups, there was only a slight increase in the older groups. Regarding stomach, colorectal and lung cancers, the proportion of local and in situ stage had similarly increased in the 65-79 years and 80 years and older age groups compared with younger groups, despite lower exposure to cancer screening. Regarding breast and cervical cancers, the increases in local and in situ cancer paralleled the increase in screen-detected cases. These findings suggest that the increases in early stage stomach, colorectal and lung cancers might be due not only to the expansion of screening programs but also the development of clinical diagnostic imaging or other reasons. The increases in local and in situ stage breast and cervical cancers seemed to be due to the expansion of screening. Continued monitoring of trends in cancer incidence by clinical stage may be helpful for estimating the effectiveness of screening.