Influence of Race on Microsatellite Instability and CD8.sup.+ T Cell Infiltration in Colon Cancer

• Published in: PloS one Vol. 9; no. 6
• Main Authors: Carethers, John M, Murali, Bhavya, Yang, Bing, Doctolero, Ryan T, Tajima, Akihiro, Basa, Ranor, Smith, E. Julieta, Lee, Monte, Janke, Ryan, Ngo, Tina, Tejada, Ruth, Ji, Ming, Kinseth, Matthew, Cabrera, Betty L, Miyai, Katsumi, Keku, Temitope O, Martin, Christopher F, Galanko, Joseph A, Sandler, Robert S, McGuire, Kathleen L
• Format: Journal Article
• Language: English
• Published: Public Library of Science 23-06-2014
• Subjects: African Americans; Cancer genetics; Colon cancer; Mortality; T cells
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0100461

African American patients with colorectal cancer show higher mortality than their Caucasian counterparts. Biology might play a partial role, and prior studies suggest a higher prevalence for microsatellite instability (MSI) among cancers from African Americans, albeit patients with MSI cancers have improved survival over patients with non-MSI cancers, counter to the outcome observed for African American patients. CD8.sup.+ T cell infiltration of colon cancer is postively correlated with MSI tumors, and is also related to improved outcome. Here, we utilized a 503-person, population-based colon cancer cohort comprising 45% African Americans to determine, under blinded conditions from all epidemiological data, the prevalence of MSI and associated CD8.sup.+ T cell infiltration within the cancers. Among Caucasian cancers, 14% were MSI, whereas African American cancers demonstrated 7% MSI (P = 0.009). Clinically, MSI cancers between races were similar; among microsatellite stable cancers, African American patients were younger, female, and with proximal cancers. CD8.sup.+ T cells were higher in MSI cancers (88.0 vs 30.4/hpf, P<0.0001), but was not different between races. Utilizing this population-based cohort, African American cancers show half the MSI prevalence of Caucasians without change in CD8.sup.+ T cell infiltration which may contribute towards their higher mortality from colon cancer.