Real-World Patient Characteristics, Treatment Patterns, and Outcomes of HR+, HER2- Early Breast Cancer Patients in Japan: An Analysis with National Database(NDB).

Real-world evidence for clinical outcomes and treatment patterns in patients with hormone receptor-positive(HR+)and human epidermal growth factor receptor 2-negative(HER2-)early breast cancer(EBC)in Japan is limited. We aimed to provide recent evidence in this population using the National Database of Health Insurance Claims and Specific Health Check-ups of Japan(NDB). Adults ≥20 years old who were diagnosed with HR+/HER2- breast cancer and underwent breast resection surgery were followed up. Patient characteristics and treatment patterns were evaluated. Durations of overall post-operative endocrine therapy(ET)and luteinizing hormone-releasing hormone(LH-RH)agonist therapy, and time to metastasis/recurrence after surgery were analyzed using Kaplan-Meier method. Overall, 294,904 patients were included. Cyclophosphamide and tamoxifen were the most common peri-operative chemotherapeutic and ET drugs. Median(95% confidence interval[CI])duration of post-operative ET and LH-RH agonist therapy was 5.01(5.01-5.01)years and 2.13 (2.12-2.14)years, respectively. Five-year cumulative rate(95% CI)of any recurrence was 8.6%(8.5-8.7), visceral metastasis being the most common. Nation-wide treatment patterns were described, which were consistent with guideline recommendations for patients with HR+, HER2- EBC. Further discussion is required to delay metastasis/recurrence and improve clinical outcomes(Fig. 1: Plain language summary of the study).