Abstract P1-09-03: Relative radioresistency in triple negative tumors in the SweBCG91-RT randomized clinical trial

Introduction: Breast-conserving surgery (BCS) with adjuvant whole breast radiation therapy (WBRT) is the standard treatment for a majority of early breast cancer patients. No predictive biomarkers for RT are in use and most patients are cured by surgery alone, and are thus over-treated. Further, some patients suffer a relapse despite WBRT, and may have benefited from mastectomy or more aggressive postoperative treatment. Gene expression tests can be used to predict risk of distant recurrence and effect of adjuvant systemic therapy, and can reveal the intrinsic subtype of the tumor. A surrogate method of determining intrinsic subtype based on high quality centralized immunohistochemistry (IHC) has been proposed with criteria set up by the St Gallen consensus group 2013. The intrinsic subtypes provide prognostic information and are treatment predictive for chemotherapy, but the predictive potential for WBRT has not been conclusively determined.Aim: To evaluate the effect of WBRT on ipsilateral breast tumor recurrence (IBTR), in patients with tumors of different intrinsic subtypes.Methods: Tumor tissue from FFPE blocks were collected from 1003 breast cancer patients with node negative, stage I-II disease, randomized to BCS with or without WBRT, in the randomized SweBCG RT-91 trial between 1991-1997. Systemic adjuvant treatment was administered according to regional guidelines, but was sparsely used. Median follow-up was 15.2 years. Tissue microarrays were constructed and stained...
Source: Cancer Research - Category: Cancer & Oncology Authors: Tags: Poster Session Abstracts Source Type: research