Development of a molecular assay on FFPE samples to predict recurrence of stage II colon cancer

A52

The 5 year survival rate for patients with Stage II colon cancer is approximately 75%. Using gene expression profiling of 74 primary tumors from Stage II patients with outcomes, we identified a 23-gene signature that provides a better prediction of individual risk for recurrence. The gene signature was validated in an independent group of 123 Stage II patients. The 23-gene signature proved to be highly informative in identifying patients with distant metastasis (hazard ratio, HR 2.56; 95% confidence interval CI, 1.01 - 6.48), even when corrected for the traditional prognostic factors (HR, 2.73; 95% CI, 0.97 - 7.73). Furthermore, we developed a real time quantitative (RTQ)-PCR assay for this gene signature using fixed paraffin-embedded (FPE) tumor tissues. The RTQ-PCR assay was tested in 110 patients and was a strong prognostic factor in both univariate (HR, 6.55; 95% CI, 2.89 - 14.8) and multivariate analyses (HR, 13.9; 95% CI, 5.22 - 37.2). Our results identify and validate the prognostic gene signature for Stage II colon cancer patients and show the feasibility of testing the gene signature using standard pathology specimens. The ability to identify colon cancer patients that have an unfavorable outcome demonstrates a clinical relevance that may help patients at high risk for recurrence who require more aggressive therapy.