Abstract B35: Molecular characterization of colorectal tumors from Puerto Rican Hispanic patients

Background and Objectives: Accumulating evidence supports that colorectal cancer (CRC) is comprised of different genetic diseases affecting the same organ. The molecular classification of CRC is evolving as we gain a comprehensive knowledge about the mechanisms and processes resulting in colorectal carcinogenesis. Tumors display distinct characteristics depending on the molecular subtype, which may affect response to treatment, prognosis, and survival. CRC is the leading cause of cancer deaths among Puerto Rican Hispanics (PRH). The aim of this study was to characterize colorectal tumors at a molecular level in a cohort of PRH in order to determine the prevalence of molecular markers. Methods: The molecular markers evaluated were microsatellite instability (MSI), CpG island methylation phenotype (CIMP), and mutations in KRAS and BRAF oncogenes. In addition, HPV infection status was assessed, as it has been associated with CRC. Sociodemographic and clinicopathological characteristics were evaluated according to MSI, CIMP, KRAS/BRAF mutation and HPV-status using Pearson9s Chi-Square and Mann-Whitney U-test. Results: A total of 201 CRC tumors were included in our study. Of the evaluated tumors 2.6% (n=3) showed MSI and 1.8% of the studied tumors had CIMP high phenotype (n=2). The incidence of KRAS and BRAF mutations for our study was 30.6% (n= 38) and 9.2% (n=11), respectively. Furthermore, KRAS positive individuals were more likely to have private or Medicare insurance ( p =0.017). In addition, BRAF mutation-positive tumor were more likely to be poorly differentiated when compared to BRAF mutation-negative tumors ( p =0.009). HPV infection was not associated with any molecular characteristics examined. Conclusions: We present for the first time the molecular characterization of CRC tumors in PRH. The observation of a different molecular signature for the CRC tumors (low MSI, CIMP Zero and mainly wild-type for KRAS and BRAF ) suggests that CRC in this population might be driven by additional genetic, epigenetic and environmental factors than other racial/ethnic groups. Citation Format: Yaritza Diaz-Algorri, Julyann Perez-Mayoral, Maria Gonzalez-Pons, Natalia Rodriguez, Belisa Suarez, Giancarlo Colon, Javier Sevilla, Daphne L. Jorge, Xavier Llor, Rosa Xicola, Luis Tous, Jose S. Reyes, Marla Torres, Ajay Goel, Segundo Rodriguez, Marcia Cruz-Correa. Molecular characterization of colorectal tumors from Puerto Rican Hispanic patients. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr B35.