Cell-Free DNA Analysis With Clinicopathologic Factors for Early Detection and Refining Lymph Node Metastasis Risk in T1 Colorectal Cancer: Results From the COSMOS-CRC Study

PURPOSE The Shield test is a blood-based assay that uses multimodal analysis of cell-free DNA (cfDNA) to enable noninvasive colorectal cancer (CRC) detection. The aim of this study was to assess the diagnostic performance of the cfDNA test for CRC and advanced precancerous lesions (APLs) and evaluate its potential clinical utility, particularly in early-stage disease. METHODS In this prospective, multicenter study, 451 patients with histologically confirmed CRC or APLs were enrolled across eight institutions. Blood samples collected before treatment were analyzed using the cfDNA test (Shield, Guardant Health, United States). We assessed the sensitivity of the test for different CRC stages and APLs. In addition, we examined the correlation between test positivity and clinicopathologic factors in stage I and T1 CRC. RESULTS The test showed 87.9% sensitivity for CRC overall, with stage-specific sensitivities of 71.2% for stage I and 97.4% for stages II-IV. Sensitivity for APLs was 37.0%. In stage I CRC, test positivity was significantly associated with tumor depth (T2: 88.6% v T1: 59.7%, P < .01). Among 70 patients with T1 CRC, the test detected all to have lymph node metastasis (LNM; 100% sensitivity). Compared with guideline-based pathologic criteria, the cfDNA test achieved higher specificity for LNM prediction (38.7% v 11.3%), thereby potentially reducing the frequency of unnecessary radical surgery from 78.6% to 54.3%. CONCLUSION This cfDNA blood-based test shows a robust diagnostic performance in CRC detection. It may improve risk stratification and support more tailored clinical decision making, particularly in the management of T1 CRC.