Abstract A31: Prognostic microRNA biomarkers for recurrence of stage II colorectal cancer

Reliable prediction of recurrence in stage II colorectal cancer (CRC) patients is a major unresolved clinical need as recurrence is often the ultimate cause of death in these individuals. Several mRNA and DNA prognostic markers have been evaluated and, to date, none have been recommended by oncology groups due to poor specificity and sensitivity. MicroRNA (miRNA) have been shown to regulate fundamental cellular processes and have been implicated in several cancer types, including CRC. We used a microarray platform to examine the expression of more than 600 miRNAs in tumors from stage II patients with or without recurrence. Using an exploratory sample set of 12 tumors (6 nonrecurrent and 6 recurrent), we identified several miRNAs that were significantly deregulated in tumors from recurrent patients compared to non-recurrent patients. We used RT-qPCR to interrogate the differentially expressed miRNAs on the original 12 samples plus an additional set of 39 stage II CRC tumors that were not used in the initial miRNA discovery process. Using cross-validation, we derived a miRNA-based classifier that was strongly associated with recurrence (hazard ratio (HR), 3.83; p=0.005). We further evaluated associations of MSI status and mutations in KRAS, BRAF and PIK3CA genes with recurrence (n=39). Multivariate Cox analysis revealed that only the miRNA classifier was significantly associated with recurrence (HR 3.08; p=0.03). Interestingly, the combination of the miRNA classifier and mutant KRAS status was highly predictive of recurrence (p Citation Information: Clin Cancer Res 2010;16(14 Suppl):A31.