Abstract P2-12-03: BRCA1/2 testing in an urban population of black women (BW)
Authors: Lynce F , Stein JE , Demarco T , Isaacs C , Smith KL 
Published: August 2014

Background: Current indications for BRCA1/2 testing do not vary by race or ethnicity except for Ashkenazi Jewish individuals. Uptake of BRCA1/2 testing is low in BW, despite the presence of risk factors for BRCA1/2 mutations such as diagnosis of breast cancer (BC) at a young age and triple negative breast cancer (TNBC). The prevalence of BRCA1/2 mutations in BW is not well defined.

Aims: To determine the prevalence and predictors of deleterious BRCA1/2 mutations and variants of uncertain significance (VUS) in an urban population of BW, to describe preventive measures taken by BW with deleterious BRCA1/2 mutations and to describe the timing of genetic testing in BW with BC.

Methods: We performed a retrospective study of all BW, defined as women who self-identified as black, African or African-American, who underwent genetic risk evaluation at two hospitals in Washington DC from 2006-2012. We collected data on age, insurance, BRCA1/2 test results, preventive measures taken after receipt of test results, oncologic history and family history (FH), defined as a first or second degree relative with BC diagnosed at age ≤ 50 and/or a first or second degree relative with ovarian cancer (OC) diagnosed at any age.

Results: 211 BW received genetic counseling during this time period, 85.8% at MedStar Washington Hospital Center, and 14.2% at MedStar Georgetown University Hospital. 73% were affected (148 BC, 6 OC). Among those with BC, 14.2% had TNBC. Median age was 48 years (range 24-83). BRCA1/2 testing was performed in 70.1% (119 BC, 6 OC, 23 unaffected). Deleterious BRCA1/2 mutations were identified in 12.2% (18/148) of BW (10 BRCA1, 8 BRCA2). VUS were identified in 9.5% (14/148) of BW (3 BRCA1, 11 BRCA2). 15.2% of BW tested in 2006-2009 had VUS compared to 4.9% of BW tested in 2010-2012. 64% of VUS have been reclassified, all as benign polymorphisms except for one. BRACAnalysis Large Rearrangement Test (BART) was performed in 20.9% but did not identify any mutations. Deleterious BRCA1/2 mutations were identified in 28.5% of BW with TNBC who underwent BRCA1/2 testing, with higher prevalence among those diagnosed at younger ages (≤ age 50: 45.5%, ≤ age 60: 40%). Deleterious BRCA1/2 mutations were identified in 75% of BW with TNBC diagnosed ≤ age 50 and a positive FH. Following receipt of test results, 28% of BW found to have deleterious BRCA1/2 mutations underwent prophylactic oophorectomy and 33% underwent prophylactic mastectomy within the study time period. BRCA1/2 counseling was performed prior to definitive breast surgery in 40.5% of BW affected with BC. 11.1% of BW with BRCA1/2 mutations were underinsured and received testing under grant support.

Conclusions: In this retrospective study of a large population of BW who underwent genetic risk evaluation, the prevalence of deleterious BRCA1/2 mutations was 12.2%. A very high prevalence was seen in BW with TNBC, particularly in the presence of a FH. As expected, identification of VUS decreased over time. Inadequate insurance coverage remains a barrier to genetic testing among BW. (Supported by the Familial Cancer Registry at LCCC P30 CA51008-17).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-12-03.