Several retrospective subgroup analyses revealed potential prognostic and predictive biomarkers based on tumour DNA and clinical characteristics, such as the relevance of the molecular status, i.e., alterations other than KRAS exon 2, such as KRAS exon 3-4, NRAS exon 2-4 and BRAF V600E, or primary tumour sidedness19–23. This evidence concerns the gene NRAS and neoplasm.