When there is a deficiency of folate, uracil replaces thymine in DNA, which may lead to DNA strand breaks and hypomethylation within the hepatic p53 tumor suppressor gene, thereby increasing the risk of cancer. Studies have revealed that patients suffering from ovarian, pancreatic, colorectal, head and neck squamous cell carcinomas, and acute lymphoblastic leukemia have higher levels of homocysteine. Moreover, rapid proliferating tumor cell lines exhibited an increase in homocysteine levels, whereas plasma homocysteine levels declined when tumor cells began to die.