In summary, this meta-analysis suggests that MTHFRC677T polymorphism is associated with increased breast cancer, gastric cancer, and hepatocellular cancer risk in Asians, is associated with increased gastric cancer, multiple myeloma, and NHL risk in Caucasians, is associated with decreased AALL risk in Caucasians, is associated with decreased CALL risk in Asians, is associated with increased breast cancer risk in Asians, is associated with decreased colon cancer risk, and is associated with decreased colorectal cancer risk in male population.
An interaction was observed between the MTHFRC677T polymorphism and freshwater fish consumption on colon cancer risk (P value for interaction = 0.031).
Homocysteine could be considered as a tumor marker in SHMT1 1420 wild-type (CC) CRC patients in Dukes' stage C and D. Further studies need to clarify why SHMT1 and MTHFR polymorphisms are associated only with rectal and not colon cancer risk.
The C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with a decreased risk of colon cancer although it may increase the risk of breast cancer.
(2) Among males, individuals who had MTHFRC677T T/T genotype were at a significantly higher risk of developing colon cancer (age-, residence-, smoking-, alcohol drinking-, tea consumption-adjusted OR=2.15, 95%CI: 1.07-4.33) compared with those who had C677T C allele.
The MTHFR 677 T allele was associated with increased risk for proximal colon cancer (adjusted odds ratio, AOR = 1.29) but decreased risk for distal cancers (AOR = 0.87).
However, our data suggest that genetic polymorphisms in MTHFR 1,298A > C, interacting with diet, may be involved in the development of highly CpG-methylated colon cancers.
MTHFR 677T showed no association with colon cancer (OR = 0.82; 95% CI 0.28-2.05) and a nonstatistically significantly elevated risk with rectal cancer (OR = 1.51; 95% CI 0.86-2.68), and MTHFR 1298 CC genotype was found to be associated with a significantly decreased risk for both colon cancer (OR = 0.30, 95% CI 0.09-0.81) and rectal cancer (OR = 0.43, 95% CI 0.23-0.80).
Recently, methylenetetrahydrofolate reductase (MTHFRC677T and A1298C) mutations were discovered to be associated with childhood acute lymphoblastic leukemia (ALL), as well as colon cancer, lymphoma, esophageal and stomach cancer.
Adequate intake of folate was a protective factor from colon cancer (OR=0.32, 95% CI: 0.12-0.88) and MTHFRC677T polymorphism showed a statistically significant effect (OR=0.25, 95% CI: 0.06-0.93), reducing the risk of colon cancer in groups that have an intake of folate exceeding 115.64ng per 1000kcal per day.
Using data from an incident case-control study (1608 cases and 1972 controls) we investigated two polymorphisms in the MTHFR gene, C677T and A1298C, and their associations with risk of colon cancer.
The methylation level of CDKN2A was higher in cancer with the L-haplotype of MTHFR than in that with the H-haplotype when cancers of proximal origin were considered (p=0.029). hMLH1 methylation also tended to be higher in proximal colon cancers of MTHFR L-haplotype (p=0.059).
The MTHFR polymTHFR polymorphisms, especially the 677C-->T mutation, may contribute to vascular and birth defect risks, while reducing the risk of certain malignancies, such as colon cancer.
The hypothesis that these two pathways are the means by which folate modulates cancer risk is also supported by the epidemiological observation that a common polymorphism in the methylenetetrahydrofolate reductase (MTHFR; EC 1.5.1.20) gene differentially affects the relative risk of colon cancer depending on folate status, because MTHFR catalyzes the reaction that determines whether cellular folate is diverted into biological methylation or nucleotide synthesis.
Our results suggest that variation at MTHFR codon 1298 (within the COOH-terminal region) may be more important for colon cancer than variation at codon 677 (NH(2)-terminal region), and in populations where folate intake is low, wild-type MTHFR activity may increase risk for colon cancer.
Using data from an incident case-control study, we evaluated the combined effect of dietary intake of folate, methionine, vitamin B6, vitamin B12, and alcohol and various forms of the MTHFR gene on risk of colon cancer.