Secular trends of breast cancer detection rate in Japan: Age, period, birth cohort, and region effects from 2004 to 2015

Abstract

Objective The purpose of this study was to investigate the influence of age, period, birth cohort, and regional differences in the detection of breast cancer using screening data.Method Data from the Japan Cancer Society's breast cancer screening program, collected from 21 prefectural branches between 2004 to 2015, were used to generate age-specific estimates of cancer detection for women aged between 40 to 79 years. We used Bayesian age-period-cohort (APC) analyses based on the cohort table to describe the simultaneous effects of age, period, and cohort on breast cancer detection rates to understand the population dynamics underlying the detection patterns. We also incorporated region as a random effect to examine regional characteristics.Results The age effect showed bimodality in the late 40s and late 50s. The period effect decreased from 2004 to 2007 and remained constant thereafter. The cohort effect showed that the detection rate for women born between 1943 and 1958 was high. Furthermore, we found regional differences in the breast cancer detection rate: Miyazaki, Fukui, Tochigi, and Hokkaido prefectures showed higher detection rates, while Kagoshima and Chiba prefecture had lower rates.Conclusion Age effect has the strongest influence on the secular trend of breast cancer detection, and there is a regional difference in the detection rate. The present study that used screening data presented similar results to those of previous studies. The National Cancer Registry, based on the Cancer Registry Act of 2016, reports accurate national data. Similar to the National Cancer Registry data, analysis using screening data has immediacy and could be used for disease prevention.