Biomarker

A measurable feature of you or your cancer, like a gene change or protein, that can guide treatment and open doors to targeted trials.

A biomarker is something measurable about you or your cancer — often a specific gene change or protein, with names like HER2 or EGFR. Doctors find biomarkers through blood tests or by testing a sample of the tumor. Think of them as clues about what’s driving the cancer.

These clues matter because they can point to treatments aimed right at your cancer’s weak spot, instead of a one-size-fits-all approach. Many modern trials look for people with a particular biomarker, so knowing yours can open doors to trials you might otherwise miss. Biomarkers often appear in a trial’s eligibility criteria — the list of who fits the study.