The science and practice of oncology are rapidly evolving based on more complete knowledge of cancer genomes and the specific genetic events that drive cancer. This knowledge, coupled with advances in medicinal chemistry, has ushered in an era of precision oncology. Use of molecular testing followed by therapies tailored to the particular molecular landscape of a patient’s disease can allow appropriate therapies to be given to patients who are most likely to benefit, while avoiding unnecessary treatment of patients who are unlikely to benefit.  Although the availability of new cancer biomarkers is encouraging for diagnosis, prognosis and treatment decision-making, determining the clinical usefulness and selection of the appropriate testing methodologies can represent a daunting challenge for practitioners.  With the field of biomarkers rapidly advancing, clinical research directly affects how oncologists manage patients. Keeping up with advances in biomarker testing allows clinicians to offer state-of-the-art care to their patients with cancer and to better identify patients that are appropriate for biomarker-directed clinical trials.