PURPOSE : Ductal carcinoma in situ (DCIS) is common in South Korea. We evaluated the patterns of axillary surgery among patients with DCIS to highlight the need for compliance with the updated national guidelines. We also evaluated whether sentinel lymph node biopsy (SLNB) was performed in accordance with the national guidelines. METHODS : The Korean Health Insurance Review and Assessment Service-National Inpatient Sample database was searched for patients with DCIS (2009-2015) to identify axillary surgery patterns by breast surgery type, year of diagnosis, age at diagnosis, and the location a ...