Guardant Health is collecting real-world validation data for its Shield-linked multi-cancer detection (MCD) blood test, with the company aiming to refine performance and prepare for potential regulatory submission. The test is currently offered as an opt-in component to the existing Shield colorectal screening test and runs on the same platform. Guardant reported earlier clinical validation results across 10 cancer types, including 98.5% specificity and 60% sensitivity, plus 89% accuracy in signal-of-origin detection. The real-world data collection is meant to act like a “pre-study,” allowing algorithm adjustment based on intended-use performance. Regulatory context matters because the company’s MCD test is a laboratory-developed test with FDA breakthrough device designation, while Shield itself is FDA approved for colorectal cancer screening. The assay’s next phase would depend on prospective evidence and final intended-use framing.