Oncotype-DX recurrence score distribution in breast cancer patients with BRCA1/2 mutations

Oncotype-DX assay has never been validated for BRCA mutation carriers. This study compares the recurrence score (RS) distribution in BRCA-positive breast cancer patients with that of a general population (GP) of patients and reports their outcomes. Eligible patients were BRCA carriers who performed the Oncotype-DX assay. Two sets of databases were cross-linked: BRCA carriers at Rabin Medical Center and Sheba Medical Center with Oncotype-DX tests performed through Clalit Health Services HMO, from 2003 to 2015. Fifty-eight BRCA patients were included (20 BRCA1, 38 BRCA2). The GP included 1020 patients. Compared to the GP, BRCA1 patients were younger, had higher rate of grade three tumors, and higher Ki67. BRCA2 patients had lower PR index, higher rate of grade three tumors, and higher Ki67. Among the GP, 52.9, 37.9, and 9.1 % had low, intermediate, and high risk RS, respectively. Corresponding rates were 15, 35, and 50 % in BRCA1 patients, and 18.4, 52.6, and 29 % in BRCA2 patients. Subgroup analysis revealed a similar RS distribution pattern regardless of the nodal status. Median follow-up was 45 months. Four BRCA patients (7 %) developed disease recurrence. RS of these patients were in the intermediate and low range. All recurrences occurred in chemo-naïve patients who had not undergone bilateral oophorectomy. This study revealed significantly different RS distributions between BRCA patients and the GP. RS values shifted toward high and intermediate risk categories. This pattern held regardless of the nodal status and was more pronounced in the BRCA1 group.