Univariate analysis (Table 2) showed significant associations of OS with age >65 years (P=0.03), undifferentiated (grade 3) primary tumours (P=0.02), colonic vs rectal location (P=0.02), solitary metastasis (P=0.008) and BRAF mutations (P<0.0001, Figure 1). This evidence concerns the gene BRAF and neoplasm.