Glutathione S-transferase (GSTM1 and GSTT1) -dependent risk for colorectal cancer

Background: The deleted GSTT1 and GSTM1 genotypes (null genotypes) resulting in loss of transferase activity are found in 10-20% and 50-60% of the population, respectively. Patients and Methods: The GSTT1- and GSTM1-dependent risk for sporadic colorectal cancer (CRC) was studied in 247 incident CRC cases and 296 hospital-based controls. Results: The GSTT1-null genotype was found to be 1.5 times more prevalent in CRC patients (17.4%) compared with controls (11.1%) (crude OR 1.6; p=0.03). The GSTM1-null genotype was found to be equally prevalent in cases and controls (53%). Multivariate analysis showed a significant 1.7-fold risk for CRC associated with the GSTT1-null genotypes (p=0.04) and this increased to 2.9 for smokers (p = 0.02). Conclusion: This study provides evidence of gene-environment interaction and illustrates the importance of further research into the role of genetic susceptibility for CRC.