ABSTRACT
Xenobiotic-metabolizing enzymes (XMEs) – glutathione S-transferases (GSTs), N-acetyltransferases (NATs), and cytochrome P450 (CYP) – are pivotal enzymes required for the biotransformation reactions essential for cellular detoxification and protection of numerous macromolecules from the attack by reactive oxygen species, environmental carcinogens, reactive electrophiles, and chemotherapeutic agents. Genetic polymorphisms in these key enzymes have been found to be associated with the increased genetic instability leading to defective enzyme production and thereby carcinogenesis. It is a known fact that both the processes initiation and progression of the carcinogenesis are influenced by genes involved in the detoxification process. There are a number of published studies that report the relevance of SNPs in XME genes to different types of cancers, especially cancers of breast, lung, gastric, prostate, colorectal, and hepatic tissues. Considering the wide variation in the allele frequency of XME genes in different ethnic populations and their interaction with different carcinogenic pathways, the influence of the genetic polymorphisms of GSTs, NATs, and CYPs in conferring susceptibility to different cancers is deeply reviewed in this chapter.
