Biomarker and genomic testing

A look at genes, proteins, and other substances in your cancer that can inform treatment. Some targeted therapies and immunotherapies only work when a cancer has certain biomarkers. It also goes by tumour testing, genomic profiling, molecular profiling, somatic testing.

No. Biomarker testing looks at changes in the cancer itself, most of which arose during your lifetime and cannot be passed on. Inherited (germline) testing looks for mutations you were born with that raise cancer risk. Some biomarker tests can incidentally suggest an inherited change. That usually means a separate test and a genetic counsellor.

Often for cancer that has spread or come back, and routinely at diagnosis for certain types, including non-small cell lung cancer, breast cancer, and colorectal cancer. Ask whether it should be part of your care, and whether your insurance covers it.

A sample of the cancer, taken during surgery or by biopsy, or a blood draw for blood cancers or a liquid biopsy. A specialised lab returns a report of the biomarkers found and any treatments that may match. Some tests also need a sample of your healthy cells for comparison.

That your cancer has a biomarker targeted by a known therapy — approved, off-label, or in a trial. Or that it has a biomarker that would stop a therapy working, which can spare you a treatment unlikely to help. Often it finds changes that do not affect treatment decisions.

A genetic change whose effect is not known. Along with changes thought to be harmless, these are not used to make treatment decisions.

Sometimes. Some studies enrol people based on the biomarkers in their cancer rather than where it started (basket trials). Some studies include biomarker testing as part of the trial.

The biopsy may be unsafe or too small. No biomarker may match an available therapy. A matching therapy may be off-label and not covered, or only in a trial you cannot join. Even a match may not work: not all cancer cells share the same biomarkers, and other features of your body affect how a drug behaves.

Not necessarily. The biomarkers in a cancer can change. A test is a snapshot of one moment. Your provider may want to retest, for example if the cancer comes back. Mine was re-read from the raw data, not just the summary.

It varies with the test, the cancer, and the plan. For advanced cancer, some tests are covered by Medicare and Medicaid. Private insurers often cover a test when there is enough evidence it is needed to guide treatment. Tests without that evidence may be treated as experimental and not covered.