Prospective, Non-randomized, Single-arm.The objectives of this study are to evaluate cosmesis and perioperative complications associated with the use of intraoperative radiotherapy (IORT) at the time of partial mastectomy in patients with breast cancer and a prior history of radiation therapy. Secondary objectives include evaluating effectiveness of partial mastectomy with IORT, measured by local, regional and distant recurrence, mastectomy rate, and disease-specific and overall survival.