Breast cancer has become one of the most prevalent cancers among women worldwide,posing a significant burden on their health.Current standard therapies are often expensive and associated with the risk of drug resistance.Drug repurposing has gained increasing attention as a cost-effective and time-saving strategy in pharmaceutical research.Many drugs already in clinical use or undergoing clinical trials can be repurposed for the treatment of new clinical indications.Based on a comprehensive understanding of the mechanisms of action of these drugs and the pathophysiological processes of breast cancer,researchers can better identify drugs with potential anti-breast cancer properties and translate them into clinical practice.This paper provides a review of the current research on repurposing existing drugs for breast cancer treatment,summarizes the mechanisms of action of these drugs,and discusses the challenges associated with the strategy of drug repurposing.