Use of the 21 gene recurrence score (RS) assay results in patients (pts) treated with intraoperative radiation therapy (IORT) for early stage (ES) breast cancer.

e12537Background: IORT patient criteria have not been defined. Suitability criteria have been established for pts receiving accelerated partial breast irradiation (APBI) by the American Society of Therapeutic Radiation Oncology (ASTRO). Certain pts (women aged ≥ 70 with ES estrogen receptor (ER) positive (+) cancers) may not benefit from any radiation therapy (XRT) and could be treated with endocrine therapy alone. Conversely, pts with high RS (HRS) have been shown to have higher local recurrence (LR) rates which are not improved by the addition of tamoxifen when compared to placebo. Pts undergoing IORT were evaluated by ASTRO APBI guidelines and RS with a comparison of the results. Methods: Outcomes of consented pts completing IORT (11/ 2011 – 5/ 2013) per protocol in a single institution IRB approved clinical trial were reviewed. Data collection included demographics, histopathology, prognostic factors, RS, adjuvant therapy, LR, and survival. Results: 100 pts (aged 43-96, mean 63) completed IORT per pro...