Abstract PO-226: Gene expression levels correlation to colon cancer disparities amongst African and Caucasian American men
Authors: Sams Darryl A. , Marshall Dana R. 
Published: January 2022

Colorectal cancer (CRC) is the third most common cancer, for both incidence and mortality, in the United States 1 Although incidence and mortality are decreasing for all races and ethnicities in the U.S., African American (AA) males continue to disproportionately bear the burden of this disease. Socioeconomic status (SES) accounts for some of this disparity as AAs, like many underserved populations, are impacted by low socioeconomic status. Individuals with the lowest SES are 40% more likely to be diagnosed with CRC than those with the highest SES. However, SES doesn't account for all of this disparity. Significant differences in the transcriptomes of AA and Caucasian American (CA) CRC tumors have been reported (UNC reference). Publicly available databases house large numbers of previously analyzed and published studies that can be analyzed again on the background of accumulated knowledge of genes and pathways and provide new insights into the biology of those tumors that may reveal new targets for therapy. With this idea in mind, GSE28000, stored in the NCBI GEO database, was identified for further analysis. The transcriptomes had been characterized using the Agilent-014850 Whole Human Genome Microarray 4 × 44K G4112F platform. The transcriptomes for 24 AA males and 16 CA males were compared using the Biostatistical analysis performed using GEO2R. This resulted in the identification of 2150 differentially expressed, annotated, genes (p≤0.05). The differentially expressed genes were uploaded into Webgestalt and an over-representation analysis for diseases was performed using the OMIM database. A statistically significant (Benjamini & Hochberg FDR p≤0.05) group of four genes associated with CRC was identified. These genes, with log2 differential expression and p-value respectively, were PIK3CA (-0.36861932), FGFR3 (-0.83181818), DCC (0.32934659), and SRC (0.37958239). A positive log difference indicates higher expression in the tumors of AA patients. Although these data are intriguing, the inability to generalize these results from this single study were clear, so we sought to validate these results in other publicly available databases. These validation efforts are ongoing but the difficulty in drawing strong conclusions about this outcome is in the underrepresentation of AA patients in cohorts and clinical trials. African American males' high incidence and mortality rate in CRC and their low presence in clinical trials embellishes the lack of racial equity in clinical trials. A study by the Mayo Clinic in 2013 pointed out of 14,232 CRC trials enrolled, only 746 were African American (11,850 CA). These inequitable results press for the need of an increase in African Americans and other disproportionately affected groups through the cooperation amongst researchers, doctors, minorities, and cancer institutes.

Citation Format: Darryl A. Sams, Dana R. Marshall. Gene expression levels correlation to colon cancer disparities amongst African and Caucasian American men [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-226.