Background: In about 10% of breast cancer (BC) cases, a genetic mutation in the BRCA1/2 genes can be found. BCs associated with BRCA2 mutations present with positive estrogen receptor (ER) status in about 50% of all cases, whereas BCs associated with BRCA1 mutation are more aggressive and more likely to be ER-negative. Oncotype genetic profiling has become a standard of care to predict recurrence and the benefit from chemotherapy in ER positive BC. The role of Oncotype-DX in BRCA mutation-carriers is not clear. Our primary end-point is to compare the RS distribution of BRCA carriers to that of the General Population (GP). Methods: Two different data bases were crossed: the list of BRCA mutation-carriers at Rabin Medical Center (n=1,191) with the list of all the oncotype-DX tests which were performed through Kupat Holim Clalit, our HMO (n=5,491), between 2003 and 2015. Results: Patients and tumor characteristics, including Oncotype RS are shown in the Table. Conclusions: Our study indicates that among BC patients with mutations in the BRCA1/2 genes, the distribution of the RS is different from that of the GP. In these patients a larger portion of the population was shifted toward the intermediate- and high- risk groups. This was more pronounced in the BRCA1 carriers. To our knowledge this is the largest BRCA cohort in which the oncotype-Dx RS has been reported.

*All Oncotype tests which were performed for patients at our institute. **The BRCA groups were compared to the non-BRCA group.