What is the difference between tumor testing and inherited genetic testing?

Both are called genetic tests, but they answer different questions. According to the National Cancer Institute, tumor testing — also called biomarker or somatic testing — looks for changes in a person's cancer cells to help choose treatment. It is for people who have cancer.

Inherited (germline) testing looks for changes present in every cell of the body from birth that raise cancer risk. Because these changes can be passed to children, results carry information for blood relatives, and testing can be considered by people with or without cancer.

The samples differ too. Tumor testing uses a piece of the cancer, from a biopsy, surgery, or a blood-based liquid biopsy. Inherited testing uses healthy cells, usually blood or saliva. Most changes found in a tumor are acquired during life and are not passed on, while inherited changes are the ones that can be passed to family.