Germline genetic testing to predict drug response and toxicity in oncology--reality or fiction?

In addition to 6-mercaptopurine, 5-fluorouracil and irinotecan, the United States Food and Drug Administration (US FDA) has recently recommended label change for tamoxifen, to include pharmacogenetic information on treatment outcome. With the increasing availability of pharmacogenetic testing, on germline as well as somatic mutations, oncologists are now able to identify individuals at risk of severe treatment toxicity or poor treatment response. However, there are still knowledge gaps to fill before rationalised therapy based on pharmacogenetics can be fully integrated into clinical practice. This review provides an overview on the application of pharmacogenetic testing for germ line mutations in oncology to predict response and toxicity.