Abstract 3891: Early real-world experience with repeat multi-cancer early detection (MCED) testing

Abstract Background: An MCED test (Galleri®, GRAIL, LLC, Menlo Park, CA) has been in clinical use since April 2021. We previously reported the results of screening the first ~53, 000 individuals in the US with this test from real-world (RW) practice. Here, we report the RW experience with repeated MCED testing in ~5800 individuals. Methods: This MCED test analyzes targeted methylation in cell-free DNA and uses machine learning to detect a Cancer Signal (CS) and determine its Cancer Signal Origin (CSO). We analyzed results returned through August 2023 for those with a “No Cancer Signal Detected” (NCSD) result in Year 1 and an additional consecutive test. We excluded tests from clinical studies and sites that limited data sharing. Systematic collection of outcomes was attempted for all cases with a “CS detected” (CSD) result and continues via a quality assurance (QA) program. Results: In this RW cohort, a second test was ordered in 5794 individuals (58% male, average age=61. 3 y, range: 24. 0-89. 0 and 42% female, average age=60. 5 y, range: 23. 0-89. 0). Median interval between blood draws was 12. 9 months, and 81% (4693/5794) were tested 10-18 months after the initial test. Among the 5794, 26 received a CSD result in the second test, of which 20 were within 10-18 months, corresponding to a CSD rate (CSDR) of 0. 45% (95% CI 0. 31%-0. 66%; 26/5794). The CSDR was slightly higher in males (0. 50% 0. 32%-0. 81%; 17/3367) vs females (0. 37% 0. 2-0. 7%; 9/2427) and was lower than the Year 1 CSDR of 0. 95% (95% CI 0. 87-1. 0; 510/53, 744). The top CSOs reported during second tests were: Lymphoid, Head anus, head Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3891.