MTHFR and cancer: A number of epidemiological studies have shown that many single-nucleotide variants (SNVs) in DNA repair genes and their intergenic regions are associated with various cancer risks25, and that SNVs in inflammation-related genes (TGF-β1, TNF, and ILs), stress response-related genes (MTHFR and HSPB1) and angiogenesis-related genes (VEGF) are also involved in the toxicities of radiation therapy26, 27, suggesting that it will be difficult for researchers in the field of radiation science to determine whether or not they are involved in individual differences in radiosensitivity.