This study includes people who may or may not receive radiation therapy as part of their normal medical care. The radiation treatment is not part of the research and is the usual treatment decided by their doctors.

People who receive radiation therapy will give small blood samples before starting radiation, at the end of radiation, and about six months later. People who do not receive radiation therapy will give blood samples after surgery and again about eight months later.

The blood samples will only be used for research. They will help researchers learn more about how treatment affects the body, but the results will not be used to make decisions about a participant's medical care.

Breast cancer

People can join this study if they are women between 18 and 50 years old who are having surgery for breast cancer. The surgery may be a mastectomy, which removes the breast, or a breast conserving surgery that removes only the cancer and a small amount of surrounding tissue. Women with any type of breast cancer may be eligible to participate.

The purpose of this study is to collect blood samples from young women with breast cancer. Researchers want to learn how radiation therapy and other breast cancer treatments affect a part of the body called the thymus gland, which helps the immune system work properly. By studying these blood samples, researchers hope to better understand how cancer treatments may change the immune system and help improve care for future patients.