Exploratory Endpoints:Investigation into potential correlations between the activity of the combination regimen of panitumumab and GEMOX (P-GEMOX) on molecular markers. Depending on the availability of tumor tissue, the biomarkers will be analyzed with the following priority: EGFr expression, nucleotide changes in EGFr and BRAF cancer genes, mutations of other genes involved in the activation of the EGFr pathway; EGFr gene amplification).