Direct medical costs of breast cancer by subtype and stage in Korea: a patient-level retrospective cohort analysis

With the emergence of increasing subtype-specific treatments for breast cancer, the need for subtype-based cost assessments have been highlighted, given the lack of detailed molecular data in prior cost analyses. Therefore, this study aimed to estimate medical costs among Korean patients with breast cancer according to molecular subtypes and stages of disease progression. This retrospective cohort study estimated the annual medical costs of 13,797patients with breast cancer by molecular subtype and disease stage using the Korea-Clinical Data Utilization Network for Research Excellence (K-CURE) dataset, a linked dataset of national insurance claims and cancer registry records (2007–2019). We performed a generalized estimating equations (GEE) analysis to evaluate the impact of clinical characteristics on costs. Furthermore, the compound annual growth rate was calculated to assess cost trends across key treatment modalities (e.g., surgery, radiotherapy, adjuvant chemotherapy, and targeted therapy). Breast cancer expenditures were heavily front-loaded, with annual costs in years 2–5 dropping to 28%–30% of Year 1 expenditures. Conversely, total costs escalated over time; first-year treatment expenditures in 2019 were 1.73 times as high as those than in 2012. Key drivers of multi-year expenditure included targeted therapy, radiotherapy, and clinical complications such as stage IV diagnosis. Surgery rates were near-universal (98%–100%) across all subtypes. Radiotherapy usage increased from 75% (2012) to 78% (2019) but remained lower for HR−/HER2+. Targeted therapy was received by 46%–83% of HER2 + patients, peaking in the HR−/HER2 + subtype. Adjuvant chemotherapy for HR+/HER2 − patients declined from 65% to 45% (CAGR: −4.46%) but remained stable in other subtypes. Breast cancer expenditures in South Korea are heavily front-loaded during the first year post-diagnosis, driven by intensive treatments. National healthcare programs should implement subtype-specific, reimbursement policy to address the future economic burden breast cancer.