On the other hand, in a metanalysis of 2,402 colorectal cancer patients treated with 5-FU-based chemotherapy who alternatively reported clinical benefit outcomes and/or adverse events, Jennings BA et al. observed a weak association between MTHFR C677T and dismal outcomes [46], whereas a positive correlation between MTHFR SNPs (C677T and A1298C) and response to fluoropyrimidines was shown in 815 Caucasian patients with colo-rectal cancer [47]. Here, MTHFR is linked to colorectal cancer.