User Notification Account Blocked After Policy Violation

Biomarker testing is becoming a routine part of cancer care, offering patients a more tailored approach when deciding on therapies.

What biomarker testing involves

Also called tumor or molecular testing, it looks for specific genes, proteins and other substances inside cancer cells. The National Cancer Institute explains that these markers can indicate how a tumor may respond to certain drugs.

Every cancer displays a distinct pattern of biomarkers. Some directly influence the effectiveness of targeted treatments, allowing doctors to recommend options with a higher likelihood of success.

Unlike inherited genetic testing, which examines hereditary mutations that increase cancer risk, the procedure focuses on changes that arise in the tumor itself over a person’s lifetime. This distinction means the results reflect the current state of the disease rather than predisposition.

How the test guides treatment decisions

In precision medicine, the presence of particular biomarkers can determine eligibility for targeted therapies or immunotherapies. For instance, patients whose tumors carry certain markers may qualify for drugs that would otherwise be ineffective.

Results can also open doors to clinical trials. Studies such as NCI‑MATCH and the pediatric MATCH program enroll participants based on specific biomarkers rather than cancer type, matching treatments to the genetic alterations found in the tumor.

Physicians typically recommend testing for advanced cancers—those that have spread or recurred after initial treatment. It is also standard at diagnosis for some cancers, including non‑small cell lung, breast and colorectal cancers.

Samples are usually taken during surgery or a biopsy for solid tumors. When a traditional biopsy isn’t feasible, a liquid biopsy—essentially a blood draw—can detect tumor biomarkers circulating in the bloodstream. The specimen is sent to a specialized lab, which generates a report for the care team.

Various test formats exist. Single‑marker assays target one alteration, while multigene panels evaluate dozens at once. The Oncotype DX test, for example, assesses 21 genes to predict chemotherapy benefit in breast cancer patients. Other assays measure tumor mutational burden, a factor that may suggest responsiveness to immune checkpoint inhibitors.

Biomarker testing does not guarantee a successful outcome. Samples may lack sufficient tissue, or no actionable markers may be identified. Even when a match exists, tumors can be heterogeneous, and markers may evolve, reducing the durability of a targeted approach.