A novel molecular tool for lymph node upstaging in colon cancer patients: Results of a prospective European, multicenter study.

464^ Background: A new diagnostic semi-automated system, One Step Nucleic Acid Amplification (OSNA), was designed for the detection of cytokeratin 19 (CK 19) mRNA in lymph node (LN) metastases of colon cancer (CC) patients (Guller U et al. CANCER 2012: DOI 10.1002/cncr.27667). Recently it has been shown that occult metastases detected in pN0 patients have an adverse effect on survival based on stage migration. In this study we investigated whether pN0 patients diagnosed by standard histopathology can be upstaged by OSNA analysis to stage III. Methods: In this international, multicenter (4 institutions: CH, G [2], E) study 103 patients-originally diagnosed as pN0 by the standard use of 1 single section haematoxylin & eosin (H&E)-were subjected to OSNA analysis. LN were isolated from fresh tissue, homogenised, and directly subjected to OSNA without prior isolation of mRNA. OSNA results were provided in qualitative categories (- / + / ++), along with the exact CK19 mRNA copy number (+: 250-5000 copies, ++: >...