RecruitingPhase 3Drug trialMegestrol Acetate for Fatigue Management in T-DXd Treated Breast CancerThis study aims to evaluate whether the combination of Megestrol Acetate at the initiation of Trastuzumab Deruxtecan (T-DXd) treatment can effectively prevent and alleviate T-DXd-related fatigue, thereby improving the quality of life for advanced breast cancer patients.