Abstract C06: Implementation of Universal Colorectal Cancer Screening for Lynch Syndrome: A Population-Based Study

Abstract

Abstract Introduction: Colorectal cancer (CRC) is the leading cause of cancer death in Puerto Rico and the third one among US Hispanics. Up to 2-4% of colorectal cancer cases are caused by germline mutation in at least one of these four DNA mismatch repair (MMR) genes: MLH1, MSH2, MSH6, and PMS2. Mutations in these genes cause Lynch Syndrome (LS), the most common hereditary form of CRC. Immunohistochemistry (IHC) tests for the presence of MMR proteins and microsatellite instability (MSI) analysis is often performed on the tumor of CRC cases to screen for LS and as markers for prognosis. Universal screening of CRC for LS has been recommended by the National Comprehensive Cancer Network (NCCN) since 2014. Objective: The purpose of this study was to determine the prevalence of positive LS-screening test as determined by absence of MMR proteins in CRC since the implementation of universal tumor screening for LS in the largest private pathology laboratory in Puerto Rico. Methods: We collected the data from all CRC cases performed at Hato Rey Pathology Laboratories from September 2014 to December 2015. Pathologies performed where collected from 11 hospitals that cover the island of Puerto Rico. The data collected included results of IHC and MSI analysis as well as tumor location, gender, age, date reported and hospital. Results: A total of 317 CRC tumors were evaluated for LS-screening; with a mean age of 66 years, and 54.3% were males. IHC analysis was performed in 288 cases and of these, 11.1% demonstrated absence of one or more of the MMR proteins, compatible with a positive screening test for LS. There were 21 cases that had only MSI analysis performed and they were all reported as microsatellite stable. Conclusion: This is the first evaluation of a systematic program for Universal CRC screening for LS in Puerto Rico. Our data is consistent with results from other studies of US-Hispanics where approximately 10% of individuals of Hispanic origin with CRC have MSI. The observed prevalence of absence of MMR-proteins in our study supports universal screening of LS among Hispanics in accordance with NCCN guidelines. Citation Format: Isabel Sierra, Yaritza Diaz-Algorri, Valerie Maldonado, Kimberly Alicea, Kathia Rosado, Marcia Cruz-Correa. Implementation of Universal Colorectal Cancer Screening for Lynch Syndrome: A Population-Based Study. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr C06.