Feasibility of Pooled One-Step Nucleic Acid Amplification for Molecular Staging of Pathologically Node-Negative Colon Cancer: A Prospective Multicenter Study

Background Although conventional one-step nucleic acid amplification (OSNA) is a useful molecular-staging method, its complexity hinders its use in clinical practice. A pooled approach for OSNA (pOSNA) has been evaluated for its feasibility in pathologically node-negative colon cancer (pNNCC) for molecular staging of lymph node metastasis in clinical practice. Methods Subjects were patients diagnosed with clinical stage II–IIIA colon cancer between January 2017 and September 2018. pOSNA involved harvesting pericolic lymph nodes from fresh surgical specimens, cutting them in half, placing 50% of the nodes in a single test tube, and performing the OSNA assay. The remaining halved pericolic, intermediate, and main lymph nodes were submitted for histopathologic examination, with metastasis determined by hematoxylin and eosin staining of a cut surface of each node. Results Of the 98 enrolled patients, 92 formed the analysis set. The mean number of harvested lymph nodes per case was 24.3 (range 5–66) and the mean number of lymph nodes used for pOSNA analysis was 6.9 (range 1–35). The concordance rate, sensitivity, and specificity between methods were 89.1%, 84.6% (95% confidence interval [CI] 0.80–0.91), and 90.9% (95% CI 0.88–0.94), respectively. The pOSNA upstaging rate for node-negative patients was 9.1% (6/66), and pOSNA returned false-negative results in 15.4% of node-positive cases (4/26). Conclusions pOSNA demonstrated an upstaging rate for pNNCC equivalent to that in previous studies, suggesting its feasibility for molecular staging of pNNCC in clinical practice.