Abstract 5013: A meta-analysis of MSI frequency and race in colorectal cancer

Abstract

BACKGROUND: African Americans(AA) are at a higher risk of colorectal cancer (CRC) and some studies report a higher frequency of microsatellite instability (MSI) in their tumors while others report lower frequency compared to Caucasians. AIM: To determine and evaluate the association of race and clinical factors with MSI rate through meta- analysis. METHODS: Twenty-two studies out of 15105 (1997-2015) were evaluated after a search in different literature databases, using keywords “colorectal cancer, microsatellite instability”. We used random effect meta-analysis to calculate the MSI frequency in all studies as well as in African American and Caucasian samples. Meta-regression analysis was used to assess the univariate effect of race, gender, age, tumor location and stage on MSI rate. RESULTS: The overall MSI frequency among CRCs was 17% (95%CI: 15%-19%, I2 = 91%). The MSI rate among racial groups were 12%, 12% and 14% in AAs, Hispanics and Caucasians respectively and was not significantly different. Sub-group analysis of studies with racial information indicates MSI OR (95% CI) of 0.78 (0.58-1.06) for AAs compared to Caucasians. CONCLUSION: CRCs demonstrate an MSI frequency of 17%. MSI frequency differences between AAs and Caucasians were not pronounced, suggesting other factors contribute to the racial disparity. There is a large variation in MSI rate between different studies. Methodology approaches and biological sources of this variation should be investigated. Citation Format: Hassan Ashktorab, Sadhna Ahuja, Lakshmi Kannan, Xavier Llor, Nathan Ellis, Rosa M. Xicola, Adeyinka O. Laiyemo, John M. Carethers, Hassan Brim, Mehdi Nouraie. A meta-analysis of MSI frequency and race in colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5013.