Thus, while some studies have found that exon 2 (codon 13) mutations predict for a worse prognosis including higher recurrence and shorter survival rates,[22] others highlighted the potential value of KRAS mutations in exons 3 and 4 (codons 61, 146 and 147) rather than in exon 2, as a predictive marker for PFS [23, 24] and OS [24, 25], and Palomba et al, did not find a significant prognostic impact for mutated KRAS in a large series of 1,284 CRC patients [26]. This evidence concerns the gene KRAS and colorectal carcinoma.