Statz, Sandra

Abstract High-specificity colorectal cancer screening is desirable to triage patients <50 years for colonoscopy; however, most endorsed colorectal cancer screening tests have not been rigorously evaluated in younger populations. This prospective cross-sectional study determined the specificity of the multitarget stool DNA (mt-sDNA) test in an average-risk screening population of 45 to 49 year-olds. Specificity was the primary outcome and was measured in participants without colorectal cancer or advanced precancerous lesions [APL– advanced adenomas (AA), and sessile serrated lesions ≥10 mm], and in the subgroup of participants with negative colonoscopic findings. APL sensitivity was a secondary outcome. The evaluable cohort included those who completed the study without protocol deviations and had a usable mt-sDNA test. Of 983 enrolled participants, 816 formed the evaluable cohort, with a mean age of 47.8 (SD, 1.5) years; 47.7% were women. No participants had colorectal cancer, 49 had APL, 253 had nonadvanced adenomas (NAA), and 514 had negative colonoscopic findings. mt-sDNA test specificity was 95.2% (95% CI, 93.4–96.6) in participants with NAA or negative findings [96.3% (confidence interval (CI), 94.3%–97.8%)] in those with negative findings, and did not differ by sex (P = 0.75) or race (P = 0.36) in participants with NAA or negative findings. Sensitivity for APL was 32.7% (CI, 19.9–47.5%), with most APL (83.7%) measuring 10–19 mm and none having high-grade dysplasia. The area under the ROC curve for discriminating between APL and lesser findings was 0.72 (CI, 0.64–0.81). mt-sDNA's high specificity would help minimize risk from unnecessary diagnostic procedures in this age group. This study shows that mt-sDNA has high specificity among average-risk 45 to 49-year olds, supporting its use as a noninvasive option for colorectal cancer screening. Prevention Relevance: This study shows that mt-sDNA has high specificity among average-risk 45–49 year olds, supporting its use as a non-invasive option for colorectal cancer screening.

Abstract Background: Emerging colorectal cancer trends demonstrate increased incidence and mortality in younger populations, prompting consideration of average-risk colorectal cancer screening initiation at age 45 versus 50 years. However, screening test performance characteristics in adults 45–49 years have been minimally described. To inform the biologic rationale for multi-target stool DNA (mt-sDNA) screening in younger patients, we analyzed and compared tissue levels of methylation (BMP3, NDRG4) and mutation (KRAS) markers included in the FDA-approved, mt-sDNA assay (Cologuard; Exact Sciences Corporation). Methods: Within 40–44, 45–49, and 50–64 year age groups, archived colorectal tissue specimens were identified for 211 sporadic colorectal cancer cases, 123 advanced precancerous lesions (APLs; adenomas >1 cm, high-grade dysplasia, ≥25% villous morphology, or sessile serrated polyp; 45–49 and 50–64 age groups only), and 204 histologically normal controls. Following DNA extraction, KRAS, BMP3, and NDRG4 were quantified using QuARTS assays, relative to ACTB (reference gene). Results: None of the molecular marker concentrations were significantly associated with age (P > 0.05 for all comparisons), with the exception of NDRG4 concentration in APL samples (higher in older vs. younger cases; P = 0.008). However, NDRG4 levels were also statistically higher in APL case versus normal control samples in both the 45–49 (P < 0.0001) and 50–64 (P < 0.0001) year age groups. Conclusions: Overall, these findings support the potential for earlier onset of average-risk colorectal cancer screening with the mt-sDNA assay. Impact: These novel data address an identified knowledge gap and strengthen the biologic basis for earlier-onset, average-risk screening with the mt-sDNA assay.

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/m 2 . 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.

INTRODUCTION: Colorectal cancer (CRC) screening is broadly endorsed for individuals 50–75 years of age. Given recent increases in CRC incidence and mortality for patients <50 years old, the American Cancer Society now recommends initiation of average-risk CRC screening at age 45 (Wolf AMD CA Cancer J Clin 2018). The performance of recommended tests, including the multi-target stool DNA (mt-sDNA; marketed as Cologuard™) test, has been minimally described in populations under 50 years old. To address this knowledge gap, we conducted a retrospective study of DNA markers (KRAS, BMP3, NDRG4) included in the mt-sDNA assay to quantify and compare tissue marker levels in sporadic CRC cases and normal colon controls from patients in 45–49 and 50–64 year-old age groups. Our primary hypothesis was that mt-sDNA marker levels would be statistically similar between cases in both age groups. METHODS: Patient samples were identified from a pathology tissue archive at Mayo Clinic, excluding those with inflammatory bowel disease or familial cancer syndromes. Formalin-fixed, paraffin-embedded tissues were reviewed by a GI pathologist for 45–49 year-old (n = 90) and 50–64 year-old (n = 96) CRC cases; normal colon samples (45–49, n = 76; 50–64, n = 92) were also included for comparison. DNA extracted from core punches was blinded and processed in a randomized order. Quantitative Allele specific Realtime Target and Signal amplification (QuARTS) assays were used to quantify KRAS mutations, and BMP3 and NDRG4 methylation. Marker level in each sample was reported as the QuARTS product of mutant KRAS , methylated BMP3 or NDRG4 relative to the ACTB product in each sample, reported as a percentage. At least 60 patients per group provided sufficient power to demonstrate differences in marker levels of ±25% between case groups and between control groups using the Wilcoxon Rank Sum test. RESULTS: CRC cases in the 45–49 vs 50–64 year-old groups did not differ significantly with respect to sex ( P = 0.77) or race/ethnicity ( P = 0.06); left-sided CRC was more common in the 45–49 vs 50–64 year-old group (87% vs. 72%; P = 0.02). None of the marker levels were statistically different between cases of the younger vs older groups or between controls of these groups (Figure 1). CONCLUSION: These data support the expectation of no age-related differences in CRC detection by mt-sDNA, as the relevant molecular markers, when they occur, are present at similar levels across age groups 45–49 and 50–64 years.