Gene expression profiles in Hispanic patients with early-onset gastric cancer.

Abstract

464 Background: A larger proportion of Hispanic gastric cancer patients are diagnosed at a young age than patients of other ethnicities. Despite diagnosis at an early age, young Hispanic patients also present more frequently with advanced disease. Whether there are molecular differences between tumors from young and old Hispanic gastric cancer patients is unknown. Methods: We performed RNA-sequencing on pre-treatment tumor samples of gastric cancer patients of self-identified Hispanic ethnicity. We stratified patients into two groups: <50 years and ≥50 years. Differentially expressed genes between groups were detected using the DESeq2 package (RStudio). We performed Gene Set Enrichment Analysis (GSEA) to identify pathways that were uniquely overexpressed in each age group. Results: 57 patients were included in our study. 23 patients were <50 years and 33 patients were ≥50 years. Comparison of the top 10% most differentially expressed genes showed no clustering based on age. However, visual inspection of the top 40 most differentially expressed genes revealed 2 distinct patterns of gene expression between age groups. GSEA revealed upregulation of DNA replication, cell cycle, and DNA repair pathways in the younger patients The tumors in younger patients also had upregulation of multiple immune activation pathways. Cancers from older patients had upregulation of programmed cell death pathways. Conclusions: Early-onset gastric cancer in Hispanic patients may represent a distinct biologic process.