Characterization of germline and tumor genomic profile in unselected young black breast cancer patients.

Abstract

e13090 Background: Young black women bear a disproportionate burden of breast cancer (BC), yet there is limited characterization of these cancers based on BRCA1 and BRCA2 ( BRCA) status and tumor genomics. In this pilot study, we characterized: tumor and clinical characteristics based on BRCA carrier status and overlap of basal-like (BL) and triple negative (TN) BC. Methods: A population-based sample of 481 black women diagnosed with invasive BC < age 50 were recruited through the Florida Cancer Registry (FCR). BRCA status was determined based on germline testing. TN status was determined based on pathology reports and FCR data. Among a subset of 90 participants, gene expression profiling (GEP) was conducted on tumor samples through PAM50 analyses to classify intrinsic subtypes and risk of recurrence (ROR) scores. Results: Mean age at BC diagnosis was 41.9 (range: 25-50) and mean ROR score was 49.6 (range: 8.7-80.7). Participants included 7 BRCA1 carriers, 5 BRCA2 carriers, 67 non-carriers (NC), and 11 with no confirmed testing. Of 46 BL tumors, 33 were TN (71.7%) constituting 94.3% of TN tumors (the remaining 5.7% were Luminal A). All BRCA1 carriers had BL tumors, of which 5 were TN. Sensitivity, positive predictive value, and negative predictive value in identifying BRCA1 carrier was higher based on BL compared to TN status (Table 1). BRCA2-associated tumors included 3 Luminal A, 1 Luminal B, and 1 BL. Mean ROR score was highest among BRCA1 carriers (57.7), followed by NC (50.5) and BRCA2 carriers (41.5). Conclusions: Study findings suggest BL status predicted BRCA1 positivity better than TN status. BRCA2- (compared to BRCA1-) associated tumors were more heterogeneous with over half being Luminal A, which may explain the lower ROR among BRCA2 carriers. Additional follow-up and expansion of this cohort with collection of clinical outcomes will be useful in assessing the predictive utility of ROR scores among young black women with BC. [Table: see text]