Regional Disparities In Cancer Burden Measured From A Nationwide Cancer Registry In Japan

Tomohiro MATSUDA, National Cancer Center, Japan

1 Center for Cancer Registries, Center for Cancer Control and Information Services, National Cancer Center

Background: A national cancer registry allowing nationwide cancer registration will begin in 2016 based on the Cancer Registry Promotion Act. The Japan Cancer Surveillance Research Group measured crude national cancer incidences in Japan for the first time ahead of enactment of the Act, in order to clarify regional disparities.
Methods: Collected data for the year 2012 from all 47 prefectures were organized according to ICD-O-3 codes and logically checked for errors at the National Cancer Center. Data quality varied from registry to registry; DCO cases ranged from 2.9% to 28.5%, and M/I ratios ranged from 0.38 to 0.60. However, all registries met the criteria for inter-regional comparison.
Results: The total number of cancers in Japan in 2012 was 869,031 (all sites C00-97). Age-standardized rate (ASR, world population) was 267.2./100,000. The latest leading sites were stomach (ASR 55.7) for males and breast (ASR 64.8) for females, followed by lung, colon, prostate and liver for males, and uterine corpus, stomach, colon and lung for females. We observed clear regional disparities in incidences for some primary sites, such as stomach and liver, but not for others, such as colorectum. Disparities at these sites were associated with well-known risk factors, mainly differences in lifestyle factors. An analysis with mortality rates showed that gaps between incidence and mortality varied according to prefectures.
Discussion: The regional cancer registry was launched in all 47 prefectures, and data quality has improved rapidly as hospital-based cancer registration has become more widespread since 2006. The first challenge, to illustrate the nationwide cancer burden based on crude regional incidence in Japan, has now been successfully realized even before enactment of the Act.