3507 Background: The prognostic value of BRAF and KRAS mutations in resected CC pts remains controversial due to published studies that include stage II & III, microsatellite instability (MSI) and MSS, colon and rectal tumors, and variable treatment regimens. We examined this question in prospectively collected biospecimens from MSS stage III CC pts receiving adjuvant FOLFOX +/- cetuximab. Methods: Tumors were analyzed for BRAF V600E and KRAS exon 2 mutations, only MSS tumors were included. Three groups were defined: BRAF Mutant, KRAS Mutant and double wild-type (WT). The analytic strategy estimated study- and arm-specific prognostic effects to assess homogeneity of results, and then analysis of pooled data. Associations of mutations with time-to-recurrence (TTR), survival after relapse (SAR) and overall survival (OS) were analysed using a stratified Cox proportional hazards model. Multivariate models were adjusted for treatment and covariates (age, sex, tumor grade, T/N stage, tumor location, ECOG PS). R...