Incidence of second primary cancers in Osaka residents, Japan, with special reference to cumulative and relative risks

This study was conducted to examine the incidence rates and cumulative risks of second primary cancers in Osaka and to compare the observed number of second primary cancers with the expected number calculated using cancer incidence rates among Osaka residents. Study subjects were all reported cases aged 0–79 who were first diagnosed as having a first primary cancer between 1966–86. Incidence of second primary cancer among the study subjects was examined through to the end of 1989. The total number of study subjects was 217,307. During the follow-up period (mean duration: 3.7 years), second primary cancers developed in 5,071 patients (2.3%). Incidence of synchronous (interval