2837 Reliability of Fecal DNA Testing for Colorectal Cancer (CRC) Screening: A Retrospective Study

Abstract

INTRODUCTION: Colorectal Cancer (CRC) is the leading cause of death in the US. The gold standard for CRC screening is a Colonoscopy, which allows for diagnostic evaluation and endoscopic interventions-excision and Biopsy of polyp. In 2014 a Fecal DNA testing modality, (Cologuard; Exact Sciences), was approved by the FDA as an option for CRC screening. Fecal DNA testing is a combination of fecal immunochemical testing (FIT) and markers for abnormal DNA. The utilization of Fecal DNA testing has increased, and continues to rise due to its noninvasive technique. A diagnostic colonoscopy is recommended for all positive results. METHODS: The aim of this study is to determine the reliability of Fecal DNA testing in regards to CRC screening. This study took place in a community hospital in central Ohio, Between January 2017 and February 2019. 100 average risk individuals whom had a positive fecal DNA test were analyzed. RESULTS: 100 patients had a positive Fecal DNA test. Among them 12 patients did not undergo colonoscopy. Our results are based on patients’ (100-12 = 88) findings who underwent a colonoscopy. 64 Patients were found to have adenomatous polyps (AP), High grade dysplasia or adenocarcinoma during examination (72.73%). Out of these 64 patients whom had positive findings, 61 were APs (95.31% of total positive endoscopic findings), and 3 were high-grade dysplasia or adenocarcinoma (4.69% of total positive endoscopic findings). 24 patients were found to have no adenomas (27.27% of patients with positive stool test). CONCLUSION: When comparing findings to statistics published by Exact Sciences, data is dissimilar. Exact sciences reports approximately 13% of tests are false positives, while our data revealed 27.27% false positive tests. Although there were a large number of patients with positive testing resulting in adenoma detection, the overall reliability of this testing strategy is difficult to determine due to the large number of false positive results. Further data is needed to evaluate if this testing technique is appropriate for CRC screening.