2838 An Evaluation of the Multi-Target Stool DNA Test for Colorectal Cancer Screening in Individuals Aged 45-49 at Average Risk for Colorectal Cancer: Act Now Study

Abstract

INTRODUCTION: Due to the rising incidence and mortality of colorectal cancer (CRC) in individuals < 55 years (Siegel R, et al, JNCI, 2017), American Cancer Society (ACS) guidelines now recommend average-risk CRC screening beginning at age 45 years. The multi-target stool DNA (mt-sDNA) test, an FDA-approved screening test for average-risk individuals ≥50 years, is one ACS-recommended option for this age group. To minimize invasive testing in the younger age group, a screening test with high specificity is necessary to triage patients for diagnostic colonoscopy. To date, most endorsed CRC screening tests have not been rigorously studied in younger age groups. The objective of this study (the Act Now study [NCT03728348]) is to quantify the specificity of the mt-sDNA test in average risk individuals ages 45-49. METHODS: Act Now is an ongoing prospective, cross-sectional, multi-center study in subjects ages 45-49 at average risk for CRC. 942 subjects are targeted for enrollment and will complete a mt-sDNA test prior to undergoing a screening colonoscopy (blinded to mt-sDNA test results). Specificity for advanced colorectal neoplasia will be determined by comparing mt-sDNA test results to the most advanced finding on colonoscopy, based on procedure report and histopathological findings. Due to the low prevalence of CRC in this age group, mt-sDNA test sensitivity will be a secondary measure. RESULTS: To date, 480 subjects have completed a mt-sDNA test and screening colonoscopy. A total of 468 subjects (97.5%) have no first-degree relative (FDR) with CRC and 12 subjects (2.5%) have an FDR diagnosed at age ≥60 years. No subject has had a previous screening colonoscopy. The study population has a mean age of 47.4 years and is 48.8% female. Self-reported race includes 84.2% white, 11.5% black/African American, 3.3% Asian, and 1.0% other. Self-reported ethnicity includes 95.2% not Hispanic or Latino, 4.6% Hispanic or Latino, and 0.2% other. The mean BMI of subjects is 29.6 kg/m2. Most subjects (67.1%) have never smoked cigarettes, while 21.9% are former smokers and 11.0% are current smokers. CONCLUSION: The ongoing Act Now study will quantify the specificity of the mt-sDNA test in average risk individuals ages 45-49. Given concerns regarding the resources required to screen this age group for CRC, a noninvasive screening test with high specificity and sensitivity will help to optimize use of colonoscopy resources.