Nationwide Analysis of Treatment Patterns for Korean Breast Cancer Survivors Using National Health Insurance Service Data

Background: The National Health Insurance Service (NHIS) established a healthcare claim database for all Korean citizens. This study aimed to analyze the NHIS data and investigate the patterns of breast cancer treatments. Methods: We constructed a retrospective female breast cancer cohort by analyzing annual incident cases. The annual number of newly diagnosed female breast cancer was compared between the NHIS data and Korea National Cancer Incidence Database (KNCIDB). The annual treatment patterns including surgery, chemotherapy, radiation therapy, endocrine therapy and targeted therapy were analyzed. Results: 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 cancer patients underwent operations. Although the proportions of chemotherapy use have not changed during 2006-2014, the total number of chemotherapy prescriptions 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 patients aged >= 50 years. Conclusion: Along with the increased breast cancer incidence in Korea, the frequencies of breast cancer treatments have increased. The NHIS data can be a feasible data source for future research.