The Puerto Rico BioBank (PRBB) multi-ethnic breast cancer tissue microarray (MEBrTMA): A powerful tool for cancer research in underrepresented minorities

Abstract Introduction: There are known disparities in outcome among breast cancer patients from different ancestral backgrounds that may relate to differences in socio-cultural factors and biological factors, such as hormone receptor expression. The Puerto Rico Biobank (PRBB) of the NCI-funded Ponce Health Sciences University (PHSU) - Moffitt Cancer Center (MCC) Partnership to Advance Cancer Health Equity serves as a resource for cancer research in underrepresented Latinx populations. To better serve breast cancer researchers, the PRBB has constructed a multi-ethnic breast cancer tissue microarray (ME-BrTMA) that represents patients from four different racial and ethnic groups; 1) non-Hispanic whites (NHW), 2) non-Hispanic Blacks (NHB), 3) Hispanics treated in Florida (HF) and 4) Hispanics from Puerto Rico (HPR), as well as control tissues. Procedures: Clinical data associated with female breast cancer patients was collected from the MCC and PRBB databases. The MCC patients were further separated into three groups based on race and ethnicity: NHW, NHB, and HF. Patients who did not have a definitive positive or negative result for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) were excluded. Hormone receptor (HR) status was considered positive if ER and/or PR were positive and was considered negative if both ER and PR were negative. Descriptive statistics on the molecular subtypes were performed. Results: Preliminary analysis demonstrates that the rates of the HR+/HER2- subtype were highest among the NHW group at 73%, followed by 71% of HPRs, 69% of HFs, and 57% of NHBs. The rate of HR-/HER2- (triple negative) breast cancer was highest among the NHB group at 27%, followed by 14% of HFs, 12% of NHWs, and 10% of HPRs. While the rates of HR+/HER2+ cancers in all 3 MCC groups were within 10-11%, the rate of this subtype in HPRs was 19%. Conversely, HR-/HER2+ cancers made up 5-6% of each of the three MCC groups and 0% of the HPR group. The ME-BrTMA contains breast tissue from a subset of the four groups for which we have hormone receptor status, representing a total of 174 patients (most contributing two tumor cores, one normal core, and one stroma core) with each of the groups adequately represented. Conclusions: The proportions of breast cancer subtypes among the MCC patient populations supported established trends. The data affirmed the concerningly high rate of triple negative breast cancer among NHB populations in the United States. The wide variety of tissue samples within the ME-BrTMA make it a useful tool for future investigations. Additional chart review, RNA sequencing, and ancestry analysis using GWAS are being performed on tissues included in the ME-BrTMA, to provide additional data resources. Citation Format: Abigail E. Lantz, Allison Bahr, Edna R. Gordián, Jaileene Pérez-Morales, Marilin Rosa, Jamie K. Teer, Dung-Tsa Chen, José A. Oliveras, Julie Dutil, Teresita Muñoz-Antonia, Idhaliz Flores, W. Douglas Cress. The Puerto Rico BioBank (PRBB) multi-ethnic breast cancer tissue microarray (ME-BrTMA): A powerful tool for cancer research in underrepresented minorities [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr A068.