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To expedite the development and application of potentially transformative multicancer early detection assays, an international summit was hosted by the Mayo Clinic Cancer Center, the American Cancer Society, and the Union for International Cancer Control on World Cancer Day 2020 at the historic Mayowood Mansion in Rochester, Minnesota. Insights shared during this unique summit have been formulated into a series of expert‐authored commentaries, which accompany this introductory article.

TPS486 Background: Hepatocellular carcinoma (HCC) is a major cause of cancer-related death in the U.S. HCC surveillance is associated with improved early detection and receipt of curative treatment. However, current surveillance strategies suffer from low adherence and suboptimal sensitivity. The multi-target HCC blood test (mt-HBT) is a novel early detection assay that provides a qualitative result based on a multiparametric algorithm that incorporates information from methylation markers ( HOXA1, TSPYL5, and B3GALT6), AFP, and patient sex. Here, we describe the protocol for a prospective, multicenter clinical trial designed to investigate the performance of the mt-HBT in patients at risk for HCC. Methods: ALTernative to U/S (ALTUS) is a longitudinal, multicenter, prospective study with a targeted enrollment of 3,000 participants. The main inclusion and exclusion criteria are described in the table. Participants will receive HCC surveillance imaging (either U/S or CT/MRI) and blood collection for the mt-HBT. Those with positive U/S are anticipated to receive standard-of-care imaging follow-up with a multiphase CT or MRI, and those with a negative U/S will receive a study CT/MRI within 30 days of blood collection. Imaging interpretation is based on the CT/MRI LI-RADS (LR) v2018 categories. The primary endpoints are the overall sensitivity and specificity of the mt-HBT to detect HCC, defined as pathology-confirmed HCC or hepatocellular cholangiocarcinoma (cHCC-CCA), LR-4/5, or LR-TIV/M plus definite/probable HCC or cHCC-CCA. The secondary endpoints are mt-HBT early-stage sensitivity, and performance in a) participants with LR-5 or biopsy-confirmed HCC and b) participants confirmed non-HCC. Participants not diagnosed with a liver malignancy at visit one will continue to receive HCC surveillance, returning for a second visit ̃6 months from first blood collection. Blood will be collected after the second visit for the mt-HBT. Data on treatment will be collected for those diagnosed with HCC. Study participants and providers will be blinded to the mt-HBT results. Participants are currently enrolling across the U.S., with 60 targeted sites and an anticipated 12-month enrollment window. Clinical trial information: NCT05064553. [Table: see text]

65 Background: There is consensus that the proportion of the average-risk US population up-to-date with CRC screening (58-65%) is insufficient. However, estimates of average risk CRC screening rates are inconsistent and impacted by inclusion of higher-risk individuals, and differing study designs. Accurate measurement of population screening rates is key to addressing gaps in care and assessing the impact of newer CRC screening tests. Methods: The study included individuals aged 50-75 years in a large de-identified claims database, with continuous enrollment during year of analysis, and a variable length baseline enrollment of 1-10 years. Average-risk designation excluded higher risk diagnoses (CRC familial syndromes, colorectal polyp or history of colorectal polyp, history of/current CRC, family history of gastrointestinal cancer, and inflammatory bowel disease). Up-to-date status was assessed within guideline-based time periods: colonoscopy (10 years); FIT or FOBT (annually); mt-sDNA (3 years); flexible sigmoidoscopy/CT colonography (5 years). Analyses assessed the proportion estimated as up-to-date and examined the sensitivity to: a) patient population (average-risk only vs. including higher-risk); b) study design (yearly cross-sectional vs. cohort of 50-year-old patients; c) methods (percent in patients with 10 years of enrollment vs. Kaplan Meier (KM) of censored variable pre-screening period). Results: The cross-sectional analysis average-risk population included 5.3 million individuals. Estimates of the proportion of those up-to-date with screening guidelines for average-risk patients varied by study design, population, and estimation method. KM estimates among the average-risk population (50-75) showed 49-50% were up-to-date in each calendar year. Including higher-risk patients in the KM analysis resulted in 70% up-to-date among the mixed average+higher-risk population. Using a cohort study design (average-risk patients aged 60 with 10 years of baseline data), 65% were up-to-date by age 60. Conclusions: In the base case analysis only half of average risk individuals were up-to-date with CRC screening, a rate lower than typically cited. Sensitivity analyses resulted in substantially different estimates and demonstrate the importance of clearly communicating the methodology used to define the study population. Higher rates quoted in the lay press and medical publications may be based on mixed populations of average+higher-risk individuals or on study designs that do not represent the full population at risk.

63 Background: Population-based colorectal cancer (CRC) screening can reduce mortality by detecting and removing advanced precancerous lesions (APL) and early-stage invasive disease. One guideline-included strategy is the multi-target stool DNA test (mt-sDNA), which combines detection of methylation DNA markers (MDMs), KRAS mutations, and fecal hemoglobin. Since the mt-sDNA pivotal study was conducted, novel biomarkers have been discovered. A panel of highly discriminant MDMs ( LASS4, LRRC4, PPP2R5C, and reference marker ZDHHC1) was identified through a blinded, case-control study of archival specimens. Here, we evaluated the performance of this novel mt-sDNA panel, combined with fecal hemoglobin, in archival stool samples weighted to early-stage CRC and prospectively collected APL, simulating a screening population. Methods: The verification study featured 777 samples—210 cases (112 CRC [49 stage I, 38 stage II, 17 stage III, and 8 stage IV] and 98 APL) and 567 controls (176 non-APL and 391 colonoscopy-negative)—from three trials (NCT01397747, NCT01260168, and NCT02503631). Median APL size was 12 mm (interquartile range: 10 mm to 15 mm), with 86.7% adenomas (n = 85) and 13.3% sessile serrated polyps (SSPs; n = 13). The average age was 65.5 years for cases (57% men) and 63.2 for controls (47% men). Samples were processed through homogenization, targeted MDM capture, bisulfite conversion, and MDM quantitation using Long‐probe Quantitative Amplified Signal (LQAS). Fecal hemoglobin was quantified using enzyme-linked immunosorbent assay (ELISA). Samples were split into stratified 75%/25% training-testing sets and model outcomes were cross-validated 1,000 times. Results: Mean performance from the cross-validation analysis is summarized in the table below. Overall sensitivity was 95.2% for CRC and 57.2% for APL, with specificities of 89.8% (no CRC/APL) and 92.4% (no neoplasia). Subgroup analyses showed high sensitivity for early-stage CRC, with 93.4% at stage I and 94.2% at stage II. By APL subtype, sensitivity was 82.9% for high-grade dysplasia, 73.4% for villous lesions, 49.8% for tubular lesions, and 30.2% for SSPs. Conclusions: These data support high sensitivity and specificity for a second-generation mt-sDNA panel. A multicenter pivotal trial evaluating the panel is underway (NCT04144738). [Table: see text]

Outreach, including patient navigation, has been shown to increase the uptake of colorectal cancer (CRC) screening in underserved populations. This analysis evaluates the cost-effectiveness of triennial multi-target stool DNA (mt-sDNA) versus outreach, with or without a mailed annual fecal immunochemical test (FIT), in a Medicaid population. A microsimulation model estimated the incremental cost-effectiveness ratio using quality-adjusted life years (QALY), direct costs, and clinical outcomes in a cohort of Medicaid beneficiaries aged 50–64 years, over a lifetime time horizon. The base case model explored scenarios of either 100% adherence or real-world reported adherence (51.3% for mt-sDNA, 21.1% for outreach with FIT and 12.3% for outreach without FIT) with or without real-world adherence for follow-up colonoscopy (66.7% for all). Costs and outcomes were discounted at 3.0%. At 100% adherence to both screening tests and follow-up colonoscopy, mt-sDNA costed more and was less effective compared with outreach with or without FIT. When real-world adherence rates were considered for screening strategies (with 100% adherence for follow-up colonoscopy), mt-sDNA resulted in the greatest reduction in incidence and mortality from CRC (41.5% and 45.8%, respectively) compared with outreach with or without FIT; mt-sDNA also was cost-effective versus outreach with and without FIT ($32,150/QALY and $22,707/QALY, respectively). mt-sDNA remained cost-effective versus FIT, with or without outreach, under real-world adherence rates for follow-up colonoscopy. Outreach or navigation interventions, with associated real-world adherence rates to screening tests, should be considered when evaluating the cost-effectiveness of CRC screening strategies in underserved populations.