Participants will be breast cancer patients receiving radiation therapy at Massachusetts General Hospital. There will be two groups of patients: those receiving adjuvant radiation therapy alone following surgical tumor resection, and those receiving adjuvant chemotherapy and radiation therapy following surgical tumor resection. Patients receiving any radiation regimen detailed below in section 2b are eligible for the study. In this study the investigators will be drawing blood for beta-endorphin measurement prior to, at various times during, and following patients' treatment regimens. In addition, at each blood draw, patients will complete questionnaires that assess fatigue, mood, and pain. These questionnaires have all been validated for use in cancer patients (see "Procedures Involving Human Participants section below), and for our study, the investigators have formatted them onto computer tablets for ease of patient completion and data analysis. This study will progress as follows: