Role of Beta-Endorphin in Cancer Therapy Fatigue

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: Patients: Patients expected to receive adjuvant radiation therapy at Massachusetts General Hospital will be approached for enrollment onto this study. Two groups of patients, a chemotherapy group and a non-chemotherapy group, will be enrolled as follows: 1. Adjuvant chemotherapy followed by radiation therapy 2. Adjuvant radiation therapy without chemotherapy The enrollment goal for each group is 50 patients (total of 100 patients for the study). This calculation is based on the approximate number of 30 patients the investigators will need to achieve a sensitivity of β-endorphin changes of 5 pM being statistically significant to a p-value of\<0.05 with 95% power. Based in our finding in mice, the investigators expect β-endorphin levels to vary between individuals, and the investigators have increased sample size by 70% from our calculations to account for deviations from our β-endorphin levels estimations. Additionally, the investigators have added patients to account for a number of patient dropping out of the study, since this is a long trial for patients requiring multiple blood draws.