Single Nucleotide Polymorphisms in Obesity and Inflammatory Genes in African Americans with Colorectal Cancer

Abstract

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers in the world and has one of the highest mortality rates among all cancers. In the USA, a racial disparity exists in CRC with the highest incidence and worst survival in African Americans compared to other races. This disparity persists even after taking into account the stage of CRC at diagnosis, treatment differences, or socioeconomic status. Some argue that African Americans may have more risk factors for CRC such as higher rates of obesity and insulin resistance. However, when adjusted for diet, physical inactivity, or central obesity, increased risk factors present in African Americans are not fully explained. These observations suggest that there may be genetic or biological differences between races that confer worse CRC outcomes in African Americans. Single nucleotide polymorphisms (SNPs), which occur in a race-specific manner, influence development of obesity, insulin resistance, chronic inflammation, and CRC. SNPs alter levels of circulating inflammatory cytokines and growth promoting hormone peptides while modifying response to environmental stimuli. SNPs that occur distinctly in African American populations may provide important insights into the racial disparities observed in CRC incidence and survival. This chapter provides an overview of racial disparities in CRC and the potential contribution of SNPs in obesity and inflammatory related genes.