Abstract
Heritable variations in genes associated with drug disposition and effects (i.e., drug metabolism, transport, and therapeutic target) contribute to individual heterogeneity in drug treatment response and tolerance. The terms pharmacogenetics or pharmacogenomics, which are often used interchangeably, refer to the study of how an individual’s genetic inheritance affects the body’s response to drugs and the use of this genetic information to predict the safety, toxicity, and/or efficacy of drugs in individual patients or groups of patients. In some cases, the term “pharmacogenetics” is used to refer to the study of differing phenotypes in association with a single gene or set of candidate genes and the term “pharmacogenomics” is used to refer to genome-wide approaches for identification or discovery of the genetic factors determining differing phenotypes. Throughout this chapter, the term “pharmacogenomics” will be used in reference to this scientific discipline. Pharmacogenomics, as it relates to cancer treatment, presents particular difficulties in comparison to other therapeutic areas, in that acquired somatic mutations in the tumors may also alter treatment outcomes and, that the narrow therapeutic window of chemotherapeutic agents makes titrations in drug dose to affect response or toxicity be a suboptimal approach. The application of pharmacogenomics into the treatment of cancer could have a considerable impact on optimizing cancer treatment for individual patients and groups of patients and also developing new chemotherapeutic agents.