Pharmacogenetic tests used in oncology can be divided in 2 groups:

1. Tests determining the toxicity of chemotherapeutics such as 5-Fluorouracil, Irinotecan and Thiopurine.
   Such toxicity is caused by mutations in the genes encoding Dihydropyrimidine Dehydrogenase, UDP-Glycuronosyl transferase or Thiopurine S-Methyltransferase, respectively.
2. Tests determining the response to the treatment with specific tyrosine kinase inhibitors (TKIs).
   Such response is determined by mutations in specific tyrosine kinase genes. Only patients with a mutation in the specific tyrosine kinase will respond to treatment with the specific TKI.
   Also the development of resistance against TKIs is genetically determined by mutations in the tyrosine kinase genes.

The most prominent examples of pharmacogenetic tests used in oncology are given below.