In addition, folate participates in one-carbon metabolism, and the importance of one-carbon metabolism in the high growth rate of cancer cells has been widely accepted.[9] Methylenetetrahydrofolate Reductase (MTHFR) gene polymorphisms may regulate the expression of folate.[10] By regulating folate expression, the MTHFR gene polymorphism is considered to be associated with susceptibility to lung cancer. The gene discussed is MTHFR; the disease is cancer.