A total of 148,322 women with newly diagnosed invasive breast cancer during 2006–2014 was identified. The numbers of newly diagnosed invasive breast cancer cases were similar between the NHIS data and KNCIDB, which demonstrated a strong correlation (r = 0.995; P < 0.001). The age distribution of the breast cancer cases in the NHIS data and KNCIDB also showed a strong correlation (r = 1.000; P < 0.001). About 85% of newly diagnosed breast cancerpatients underwent operations. Although the proportions of chemotherapy use have not changed during 2006–2014, the total number of chemotherapyprescriptions sharply increased during this period. The proportions of radiotherapy and anti-hormonal therapy increased. Among the anti-hormonal agents, tamoxifen was the most frequently prescribed medication, and letrozole was the most preferred endocrine treatment in patientsaged ≥ 50 years.