Survey for incidence of cancer as a measure of outcome in the JACC Study

Background: As endpoint of cohort studies on cancer, the incidence, rather than the mortality is preferable. Of 45 areas in the Japan Collaborative Cohort Study (JACC Study), surveys for incidence of cancer were conducted in 24. Methods: The proportion of the study subjects aged 40 to 79 years in areas of survey for the incidence of cancer (65,184 persons) was 58.2% of the total subjects of the JACC Study (110,792 persons). Among the 24 areas of survey for the incidence of cancer (ASI), 10 areas were combined because of similarity. Then, we present the incidence rate of cancer among 15 ASI unified from the 24 ASI by gender according to area. We also report the completeness of the survey for cancer incidence presenting the mortality-incidence ratio (MI ratio) among the ASI. Results: Where a population-based cancer registry was utilized, the MI ratio deviated from 0.31 to 0.61 in the male subjects and from 0.15 to 0.53 in the female subjects, However, where a population-based cancer registry was not used, the MI ratio deviated from 0.25 to 0.72 in the male subjects and from 0.13 to 0.79 in the female subjects, and there was an area where the MI ratio exceeded 0.70 in both of the male and female subjects. Conclusion: Establishment of population-based cancer registries is strongly desired throughout Japan to assess risk factors of cancer development for primary prevention of cancer.