AbstractIndividuals diagnosed with metastatic triple-negative breast cancer (mTNBC) suffer worse survival rates than their metastatic non-TNBC counterparts. There is little information on survival, treatment patterns, and medical costs of mTNBC patients in Asia. Therefore, this study aimed to examine 5-year survival, regimens of first-line systemic therapy, and healthcare costs of mTNBC patients in Taiwan. Adult females newly diagnosed with TNBC and non-TNBC as well as their survival data, treatment regimens and costs of health services were identified and retrieved from the Cancer Registry database, Death Registry database, and National Health Insurance (NHI) claims database. A total of 9691 (19.27%) women were identified as TNBC among overall BC. The 5-year overall survival rate of TNBC and non-TNBC was 81.28% and 86.50%, respectively, and that of mTNBC and metastatic non-TNBC was 10.81% and 33.46%, respectively. The majority of mTNBC patients received combination therapy as their first-line treatment (78.14%). The 5-year total cost in patients with metastatic non-TNBC and with mTNBC was NTD1,808,693 and NTD803,445, respectively. Higher CCI scores were associated with an increased risk of death and lower probability of receiving combination chemotherapy. Older age was associated with lower 5-year medical costs. In sum, mTNBC patients suffered from poorer survival and incurred lower medical costs than their metastatic non-TNBC counterparts. Future research will be needed when there are more treatment options available for mTNBC patients.