Most anticancer medications have narrow therapeutic indices low overall response rates, rapid and severe systemic toxicity and unpredictable efficacy. Therefore, nowhere is pharmacogenomics research needed more than in cancer treatment to guide clinicians to better predict the differences in drug response, efficacy, resistance and toxicity among chemotherapy and targeted therapy patients, and to optimize the treatment regimens based on these differences. [4] In oncology, efficacy and safety of many chemotherapeutic drugs show substantial individual and/or population variability. It can be explained, to a great extent, by gene polymorphism encoding drug-metabolizing enzymes, drug transporters and drug targets which influence the pharmacokinetics and pharmacodynamics and affect clinical outcomes. [5,6] There are several known genes which are largely responsible for variations in drug metabolism and response. The most common are the CYP genes, which encode enzymes that influence the metabolism of more than 80% of current prescription drugs.In addition, the application of pharmacogenomics in oncology is in the discovery of biomarkers that guide selective therapy,
ABSTRACTIn a given population, there is considerable variation between individuals with regard to response to as well as toxicity of different drugs. The term "Pharmacogenetics" has largely been used in relation to genes determining drug metabolism, while "Pharmacogenomics" is a broader based term that encompasses all genes in a genome that may determine drug response. In oncology, efficacy and safety of many chemotherapeutic drugs show substantial individual and/or population variability. It can be explained, to a great extent, by gene polymorphism encoding drug-metabolizing enzymes, drug transporters, and drug targets which influence the pharmacokinetics and pharmacodynamics and affect clinical outcomes. Single nucleotide polymorphisms (SNPs) are the most studied genetic variants at present due to ease, accuracy, and reduced the cost of processing as well as due to public availability of online resources for SNPs. Candidate genes for a therapeutic and adverse response can be divided into three categories: Pharmacokinetic, receptor/target, and disease-modifying. Many anticancer drugs are evaluated for their variation in response according to germline variations. This information can be easily incorporated in day-to-day practice to improve efficacy and/or safety of these drugs. In the future, advances gained from pharmacogenetics research will provide information to guide doctors in advising just enough of the right medicine to a person -The practice of "personalized medicine."