“…[37] Conversely, blood-based molecular biomarkers, including nucleic acids, proteins, and metabolites, hold great promise for early PC diagnosis due to their ease of interpretation, convenience, and non-invasiveness with high compliance rates (> 90%). [38] As compared to upstream molecules (nucleic acids and proteins, MW > 1 000 Da) with suboptimal diagnostic performance (e.g., specificity of 75% by CA19-9), [39] small metabolites (MW < 1 000 Da) as downstream molecular biomarkers directly offer real-time phenotypic information, [5b,33b,40] potentially leading to high-performance blood tests. [41] Previous studies of metabolic biomarkers for PC diagnosis mainly relied on liquid chromatography-MS (LC-MS) and gas chromatography-MS (GC-MS), [42] limited by slow analytical speed (up to hours per sample) and large sample consumption (sub-milliliter) due to the need for chromatographic separation and purification.…”