KRAS and colorectal carcinoma: Four sets of results among the enrolled studies showed a significantly unfavorable impact of KRAS codon 13 gene mutations on OS,[14,38,40] whereas the remaining 5 sets of results failed to demonstrate any statistically significant association between KRAS codon 13 gene mutations and OS.[17,39,41] Additionally, because anti-EGFR drug therapy potentially influences OS in CRC patients due to therapeutic effects, we conducted a subgroup analysis according to whether or not patients in the enrolled studies received anti-EGFR drug therapy.