2846 Colorectal Cancer Screening in Individuals Ages 45-49 Years: Point Sensitivity of the Multi-Target Stool DNA Test

Abstract

INTRODUCTION: Colorectal cancer (CRC) incidence and mortality rates in the ≥55 year old population is decreasing, while CRC incidence and mortality is increasing in those < 55 years old (SEER Cancer Stat Facts: Colorectal Cancer. NCI, Bethseda, MD). Recently, the American Cancer Society revised its CRC screening guidelines to recommend screening initiation at age 45 years for average-risk individuals (American Cancer Society, 2018). To date, most endorsed CRC screening tests have not been rigorously studied in younger age groups. In this study, we examined the point sensitivity of the multi-target stool DNA (mt-sDNA) test in patients ages 45-49 years. The mt-sDNA test is currently FDA-approved to qualitatively detect biomarkers associated with colorectal neoplasia in individuals 50 years and older and at average risk for CRC, and data do not suggest age-related changes in sensitivity of the mt-sDNA test (Imperiale et al, 2014, NEJM). METHODS: Clinical listings of Exact Sciences-sponsored studies were queried to identify archived stool samples previously collected from individuals ages 45-49 years, with confirmed diagnoses of CRC or advanced adenomas (AA; defined as ≥1 cm, or ≥25% villous morphology or high-grade dysplasia of any size). Historical information regarding CRC risk was limited. Stool samples were collected at least 7 days after the screening colonoscopy, prior to lesion excision and any pre-surgical prep or neoadjuvant treatment. Samples were analyzed per the mt-sDNA test label instructions. Mt-sDNA test sensitivity for advanced colorectal neoplasia (CRC + AA), CRC, and AA were the primary study study endpoints. RESULTS: Archived stool was available from 13 individuals with CRC and 6 with AA. Mt-sDNA test sensitivity for advanced neoplasia (CRC + AA), CRC, and AA were 89% (17/19 samples), 92% (12/13 samples), and 83% (5/6 samples), respectively. CONCLUSION: This small study using archived stool samples from individuals ages 45-49 years without complete risk status information found that mt-sDNA test sensitivity was similar to previously reported data for individuals ages 50 years and older (Imperiale et al, 2014, NEJM), providing initial demonstration of test sensitivity in this younger population. Larger studies are needed to confirm and more broadly evaluate mt-sDNA performance characteristics in an average risk screening population in this age group.