EXERT-BCH Exercise Regimen to Improve Muscle Mass After Treatment of Breast Cancer

This study tests whether a structured exercise program can help women who have been treated for breast cancer regain and maintain muscle mass, which is often lost during cancer treatment. Muscle loss can affect strength, energy, and quality of life. **You may be eligible if:** - You are a woman between 20 and 89 years old - You have a confirmed diagnosis of breast cancer (ductal carcinoma in situ or invasive breast cancer) - You have completed cancer treatment (surgery, radiation, chemotherapy, immunotherapy, or hormone therapy) - Immunotherapy or targeted therapy is still allowed **You may NOT be eligible if:** - You are currently receiving cytotoxic chemotherapy - You have health conditions that prevent safe participation in exercise - You have metastatic (stage IV) breast cancer Talk to your doctor to see if this trial is right for you.