Mammography for Japanese women living in Australia: are current breast screening targets appropriate?

Introduction: Breast cancer is one of the most common types of cancer among women globally and screening by mammography plays a crucial role in detecting cancer. However, screening target ages may differ between countries. For example, the target group is 50-74 years in Australia and 40+ years in Japan, reflecting differences in age-specific incidence rates (ASIR). Breast cancer risk is related to the volume of mammographic breast density (MBD), which has been found to differ among ethnic groups, hence impacting on national screening policies. The thesis is aimed to investigate whether Japanese women living in Australia (JWA) are best served by the current screening policy of BreastScreen Australia. Methods: The thesis is based on findings from two studies: 1. ASIR in Australia and Japan based on secondary data; 2. The comparison of MBD between Australian women (AW), JWA and Japanese women living in Japan (JWJ). De-identified mammography is categorised independently by three specialist clinicians using the BI-RADS® (5th ed.). Bivariate and multivariate analysis were undertaken using SPSS® Statistics. Results: The results show that Australian ASIR rose sharply from age 40 years and peaked at 65-69 years. While in Japan, the highest incidence occurred at 45-49 years and declined after 50 years. In the second study, more than 65% of AW were found in the low MBD category while the majority of JWJ were in the high MBD category. The ORs demonstrated that JWA were approximately 5 times more likely and JWJ were about 15 times more likely to have high MBD compared to AW. These findings have policy implications in the context of setting breast screening targets. Conclusion: The results indicated two critical implications. Firstly, JW aged 40-49 should be included in the screening target age group. Secondly, supplemental screening should be suggested for JW mainly aged 40-49 years. The findings are also crucial for other ethnic migrant women living in Australia