Jang et al (2014) studied survival rates of Colorectal Cancer (CRC) in a Korean population in relation to 3 genetic polymorphisms, of which MTHFR mutations C677T and A1298C were included. The C677T mutation was the most common MTHFR genotype presentation by the patients in the study, showing predominance toward increased tumour size and advanced stages of cancer. These findings were not successful, as the C677T did not increase survival rates of patients.
This is potentially be due C677T having no impact on or decrease survival rates in CRC, as this mutation can increase the toxicity of anti-folate drugs commonly used in treatment. This would instead contribute to decreased survival rates, instead of aiding in overall survival.