This study, called PERSEVERE, examines how local treatment for early breast cancer affects people's health and daily lives over time. People who join the study will have early-stage breast cancer and receive treatment such as surgery and other therapies that are used before or after surgery. The study does not include people with late-stage (metastatic) breast cancer. Researchers want to learn about short- and long-term side effects that can happen during or after treatment. These may include tiredness, trouble sleeping, emotional distress, pain, or changes in heart or lung function. The study also looks at how these effects impact participants' quality of life. Participants will be asked to complete surveys about how they feel. They will also have health checks, such as heart tests, lung function tests, and blood samples. Tissue samples from surgery will also be collected. The goal is to understand better how different people respond to breast cancer treatment and find ways to support long-term recovery.