Prognostic influence of BRCA 1 somatic mutations in African Amercian versus Caucasian ovarian cancer patients.

Abstract

e17054 Background: Racial disparities in outcomes exist between African-American (AA) and Caucasian (C) patients (pts) with high grade epithelial ovarian cancer (EOC). Not all disparity is explained by socio-economic and access related issues. Many argue that differences in tumor biology also play a role. Germline BRCA mutations confer a protective effect in these pts. Immunohistochemistry (IHC) for BRCA 1 is being developed to detect somatic BRCA1 mutations. Parp-inhibitors have been approved for use in pts with germline and/or somatic BRCA mutations. We describe the first comparison of the prognostic implications of BRCA1 somatic mutation status in tumor samples taken from AA and C EOC pts who underwent primary surgery followed by systemic chemotherapy. Methods: IHC staining of whole tumor sections from AA and C pts was performed using a commercially available monoclonal antibody against BRCA1 (Calbiochem). Staining was scored as: loss, retention, or equivocal in the presence of a positive control. Retention was described as wild-type and loss or equivocal as mutation. Standard statistical analyses were used to correlate race, BRCA1 status, and survival. Results: Tumor from 33 pts (16AA and 17C) was stained and scored. Most pts had Stage III (66.7%) disease and high grade serous subtype (82%). Stage, histology, and debulking status did not differ between groups. Overall, loss of BRCA 1 occurred 16/33 (48.5%) tumors. BRCA1 was mutated more frequently in tumors from AA pts (11/16) compared to C pts (5/17) (p=.024). BRCA 1 mutation conferred a protective effect, with a trend towards improved progression free survival: 9.5 vs 15.8 mos in AA (p=0.44) and 16.5 vs. 21 mos in C pts (p=0.97). No statistically significant difference in OS was seen. Conclusions: We demonstrate that IHC for BRCA 1 mutation is feasible in a standard hospital pathology laboratory. Race based differences in somatic BRCA 1 mutation exist; mutational differences are associated with a trend in improved PFS. A larger cohort is needed to elucidate the true effect of this status on outcome. Conceivably, knowledge of BRCA 1 tumor status could be used to improve outcomes in AA pts who may be able to achieve survival numbers comparable to C pts.