Implementation of BRCA Test among Young Breast Cancer Patients in South Korea: A Nationwide Cohort Study.

Purpose: This study aimed to investigate the frequency of BRCA testing and related factors among young breast cancer patients (age < 40 years) in South Korea.

Materials and methods: We conducted a nationwide retrospective cohort study using data from the Health Insurance Review and Assessment claims. Newly diagnosed breast cancer patients younger than 40 were included. Annual BRCA testing ratios (number of BRCA test recipients/the number of patients undergoing breast cancer surgery in each year) were analyzed by region and health care delivery system. We investigated the location of breast cancer diagnosis and BRCA testing.

Results: From January 2010 to December 2020, there were 25,665 newly diagnosed young breast cancer patients, of whom 12,186 (47.5%) underwent BRCA testing. The BRCA testing ratios increased gradually from 0.084 (154/1,842) in 2010 to 0.961 (1,975/2,055) in 2020. Medical aid (vs. health insurance) and undergoing surgery in metropolitan cities or others (vs. Seoul), general hospitals, and clinics (vs. tertiary hospitals) were associated with a lower likelihood of BRCA testing. While 97.8% of the patients diagnosed in Seoul underwent BRCA testing in Seoul, 22.9% and 29.2% of patients who were diagnosed in metropolitan areas and other regions moved to Seoul and underwent BRCA testing, respectively.

Conclusion: The frequency of BRCA testing has increased over time in South Korea, with Seoul showing a particularly high rate of testing. About one-quarter of patients diagnosed with breast cancer outside of Seoul moved to Seoul and underwent BRCA testing.