External validation of a tumor derived 5-gene prognostic signature (OncoDefender-CRC) for recurrence (R) of stages I/II colorectal cancer (CRC).

3559 Background: About 10-15% of stage I and 25-30% of stage II CRC patients (pts) will recur after potentially curative surgery. Correctly identifying these ‘high risk’ pts is a significant unmet medical need. We hypothesized that a tumor genomic test would better predict the chances of tumor R within 36 months (mo) than current NCCN Guidelines (NCCN). Methods: Archival formalin-fixed paraffin-embedded primary adenocarcinoma tissues (median storage 7 yrs; range 4-15) obtained at initial curative resection (R0) were retrieved for 109 stage I/II (pT1-4 pN0 M0) colon cancer and 6 stage I (pT1-2, pN0 M0) rectal cancer pts (median age 65; range 36-90) from 2 US and 2 European sites. These sites were different from the tissue sources previously used to generate the test through genetic programming analysis of 422 CRC- and stroma-related genes. Pts had tumor R by 36 mo (n=46) or confirmed non-recurrence (NR) for ≥36 mo (n=69) after surgery; none had received neoadjuvant or adjuvant therapy. Tumor gene expressio...