The goal of personalized medicine is to tailor therapies to an individual patient with a goal of maximizing benefit and minimizing treatment related side effects. Inter-individual variability in metabolic enzymes can have a significant impact on cancer therapies. Pharmacogenomics (PGx) studies the interactions between drugs and genes, and pharmacogenomic screening tests can assess for genetic variations among individuals to personalize medicine. PGx testing identifies genes within an individual that may affect treatment, efficacy, and toxicity of drugs. PGx screening prior to chemotherapy would help identify patients with genetic polymorphisms that are at increased risk for drug toxicity and would benefit from genetic-guided dosing, resulting in decreased risk of adverse events (AEs) related to the chemotherapy. PGx testing is not routinely used in community-based oncology practices. The cost of testing as well as lengthy waits for results have limited routine use of this testing. Advances in testing have reached the point where routine preemptive testing could benefit patients with newly diagnosed cancer.