Abstract 109: Clinicopathological characterization and nutritional assessment of Hispanics with sporadic microsatellite unstable colorectal cancers.

Abstract

Abstract Introduction: Approximately 10% to 15% of all sporadic colorectal cancers have microsatellite instability (MSI). MSI has not been well studied in Hispanics, an ethnic minority at high risk for colorectal cancer (CRC). Patients with MSI tumors present with better prognosis, higher 5-year survival and limited response to 5-FU based chemotherapy, compared to microsatellite stable (MSS) tumors. The aim of this study was to define the clinic-pathologic phenotype of Hispanics with sporadic MSI CRC and to evaluate the association of dietary factors and tumor MSI-status. Methods: The case-case study evaluated the MSI status of sporadic CRC diagnosed during the period January 1, 2002 to October 31, 2012. MSI analysis was performed using six markers (BAT26, BAT25, NR21, NR22, NR24 and NR27). Tumors were classified as MSI-high if two or more of the six microsatellite repeats were mutated and MSS if none of the replicates was mutated. Frequency analysis, chi-square, Fisher's exact test and Wilcoxon rank-sum test were used for statistical analysis methods. Unconditional logistic regression was employed to estimate the odds ratio (OR) between exposures and MSI using STATA 10.0. Results: A total of 85 participants (mean age 57.5 ± 12.5 yrs, 51.8% males) were examined. 80 patients had MSS tumors, while 5 (6%) tumors had MSI. The colorectal neoplasia specimens analyzed were mostly adenocarcinomas (96.5%) located in the distal colon (72.0%) with TNM stage III (34.4%). Tumors with MSI did not significantly differ from MSS tumors with regards to gender (p=0.36), age (p=0.66), education (p>0.99), family history of CRC (p=0.58) or obesity (p>0.99). MSI tumors were more likely located in the proximal colon compared to MSS tumors (OR=12.21; 95% CI 1.4-306.6). There were no statistical significant associations between MSI and reported consumption of dark green leaf vegetables (2-4 times/week) (OR=0.77; 95% CI 0.11-6.88), fruits (≥ 7 times/week) (OR=3.54; 95% CI 0.24-108.52) and red meats (once per day) (OR=1.08; 95% CI: 0.04-9.55). Conclusions: We report a lower prevalence of MSI in Hispanics with sporadic CRC than other Western populations. As previously reported in other non-Hispanic populations, MSI tumors were mostly located in the proximal colon. There were no statistical significant associations between sociodemographic, clinical and nutritional characteristics and MSI. Ongoing efforts to continue to examine additional Hispanic patients are underway to determine if dietary patterns in Hispanics are associated with CRC MSI status. Citation Format: Yaritza Diaz-Algorri, Sofia Margarita Lopez-Diaz, Maria del Mar Gonzalez-Pons, Katerina Freyre, Maritere Olascoaga, Sylvia B. Saldaña-Villafañe, Mercedes Y. Lacourt-Ventura, Sharon C. Fonseca-Williams, Raul D. Bernabe-Dones, Xavier LLord, Rosa Xicola, Katherine Tucker, Marcia R. Cruz-Correa. Clinicopathological characterization and nutritional assessment of Hispanics with sporadic microsatellite unstable colorectal cancers. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 109. doi:10.1158/1538-7445.AM2013-109