Effectiveness of the Korean National Cancer Screening Program in Reducing Breast Cancer Mortality

Abstract

Background: High incidences of breast cancer are reported in Asian women in their forties, and it is not clear whether mammographic screening for breast cancer reduces mortality among them. Nevertheless, the Korean National Cancer Screening Program (KNCSP) has implemented breast cancer screening for individuals aged 40 years and older. This study evaluated the effect of breast cancer screening in Korea. Methods: We conducted a prospective cohort of cancer-free Korean women who were invited to participate in the KNCSP between 2002 and 2003. We followed them to identify breast cancer incidence and cancer death by 2014 and 2015, respectively. Information on mammographic screening, breast cancer diagnosis, death, and causes of death was linked by identification numbers. Poisson regression was performed to estimate mortality rate ratios (MRR) for breast cancer among screened to non-screened women. Findings: A total of 8,293,240 women aged 40-79 years were included in the analysis. Breast cancer incidence rates were 84.41 and 82.88 per 100,000 women-years for screened and non-screened women, respectively, with an adjusted rate ratio of 1.09 (95% CI, 1.08-1.11). Breast cancer mortality rates were 5.81 and 13.43 per 100,000 women-years for screened and non-screened women, respectively, with an adjusted MRR of 0.43 (95% CI, 0.41-0.44). The greatest mortality reduction was noted among women aged 45 to 54 years, and there was no observable reduction in mortality after the age of 70 years. Interpretations: The KNCSP for breast cancer has been effective in reducing breast cancer mortality for Korean women aged 40-69 years, doing so by 22%. Funding Statement: This study was supported by a Grant-in-Aid for Cancer Research and Control from the National Cancer Center of Korea (1910231-1). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: This study was approved by the Institutional Review Board of the National Cancer Center, Korea (Institutional Review Board no. NCCNCS08129).