Abstract 15699: High-Dose Anthracycline Administration and Development of Cardiotoxicity in Women With Breast Cancer: An Analysis of Real-World Data From a Nationwide Claims Database in Japan

Abstract

Introduction: Breast cancer is the most common malignancy affecting women, and the number of survivors is increasing with the advent of new therapies. However, Anthracyclines (ACs) retain an essential role in the drug treatment of breast cancer, despite their known cardiotoxicity. Although dexrazoxane, a cardioprotective agent for high-dose AC administration, has been approved in the US and Europe, it remains one of the drug-lag issues in Japan. Objective: To evaluate real-world data on the proportion of high-dose anthracycline administration and the incidence of cardiotoxicity in Japanese patients with breast cancer using a nationwide claims database. Methods. This study is a retrospective observational analysis using the Japan Medical Data Centre (JMDC, Tokyo, Japan) database, an anonymized patient-level claims database younger than 75 years old. We first identified women diagnosed with breast cancer and treatment with AC. Patients with a history of heart failure and a treatment start record of fewer than six months were excluded. After adjusting for patient background factors by propensity score matching (PSM), cardiotoxicity risk factors and outcomes were compared between the high-dose group (AC-H) and the low-dose group (AC-L). Results: Among women with breast cancer who underwent AC treatment between January 2015 and September 2020, 5.3% (255/4,831) were classified to the high-dose group. After PSM, the number of cases, age (years) and follow-up (months) in each group were as follows: AC-H group (n=254, median 51.0 [IQR: 46.0-55.0], 26.0 [14.0-52.0]), AC-L group (n=254, 51.0 [46.0-57.0], 32.5 [15.0-59.0]). The 5-year rates of mortality and heart failure in AC-H and AC-L groups were 33.1% vs 4.5% (Log-rank p < .0001) and 11.0% vs 4.3% (Log-rank p=0.003), respectively. Conclusion: The proportion of women with breast cancer who received AC in the high dose group was approximately 5%. However, compared with the low-dose group, the high-dose group had a lower survival rate and a higher incidence of heart failure. Therefore, in Japan, clinical development of cardioprotective agents for patients with metastatic or recurrent breast cancer who require high doses of AC is warranted.