MTHFR and cancer: Therefore, the variability between carriers of the 677CT/1298AA and the 677CT/1298AC genotypes, combined with the comparability between the 677CT/1298AC and the 677TT genotypes may confirm the hypothesis that the cancer risk difference between genotypes stems from disturbances in the folate metabolism pathway, and this disturbances may be driven by the gradual changed MTHFR activities.