GSTP1 and colorectal carcinoma: However, in GSTM1 gene polymorphism, high frequency of meat consumption increased risk of CRC by about four times (OR adjusted for sex and age=3.8, 95% CI: 1.6–9.1), while GSTP1 gene polymorphism showed a three-fold increased risk of CRC with high frequency of meat consumption (OR adjusted for sex and age=3.4, 95% CI: 1.4–8.1).