Biomarker testing is when doctors take samples from your body like blood or saliva and measure specific biological molecules called biological markers or biomarkers for short. Genetic testing is looking for a certain type of biomarker for changes in a person’s genes, gene expression, or chromosomes at the cellular level. The testing can also be done on tumor tissues, helping diagnose cancer, plan treatment, or monitor a treatment. Genetic testing may give information about your risk of developing a certain cancer type or if people in the same family may be at higher risk than most other people for a cancer type. Some clinical trials may require and may pay for you to have biomarker or genetic testing done before you can be accepted into the trial.