Biomarker testing and genetic testing are not the same thing, but they overlap. Genetic testing is one type of biomarker testing. Think of biomarker testing as the umbrella and genetic testing as one tool underneath it. A biomarker is any measurable characteristic in your body that signals what’s happening biologically, whether that’s a DNA mutation, a protein level, an enzyme spike, or a hormone receptor. Genetic testing looks only at DNA and RNA changes.
What Counts as a Biomarker
A biomarker is anything in your body that can be objectively measured and used as an indicator of a normal process, a disease, or how you’re responding to treatment. That definition is deliberately broad. Your blood sugar level is a biomarker. The protein troponin, which heart muscle cells release when they’re damaged, is a biomarker cardiologists use to detect heart attacks. Enzymes like creatine kinase and lactate dehydrogenase help diagnose cardiovascular disease and certain cancers. None of these involve reading your DNA.
Genetic biomarkers, by contrast, are specific DNA or RNA characteristics that indicate disease risk, tumor behavior, or how your body will process a drug. When doctors test a lung tumor for EGFR mutations, or check whether a breast cancer is HER2-positive, those are genetic or genomic biomarkers. The critical difference: these tests analyze the instructions in your cells’ genetic code, while protein or enzyme biomarkers measure what your cells are actually producing or releasing into your bloodstream.
Two Kinds of Genetic Changes
Not all genetic testing looks for the same thing. The distinction between inherited and acquired mutations matters for understanding what your results mean and who else in your family might be affected.
Germline mutations are inherited. They exist in the egg or sperm cells that created you, so every cell in your body carries them. Testing for BRCA1 and BRCA2 mutations in ovarian or breast cancer patients is germline testing. If you carry one of these mutations, your children have a chance of inheriting it too.
Somatic mutations happen after conception in ordinary body cells, not reproductive cells. A tumor might develop a KRAS mutation or a BRAF mutation that drives its growth, but that mutation exists only in the cancer cells. It wasn’t inherited and can’t be passed to your children. When oncologists send a tumor sample to a lab for molecular profiling, they’re primarily looking for somatic mutations that can be targeted with specific drugs.
Why the Distinction Matters in Cancer Care
The place where biomarker testing and genetic testing blur together most is oncology. Modern cancer treatment increasingly depends on identifying the specific molecular features of a tumor before choosing a therapy. The FDA now lists hundreds of drug labels that reference pharmacogenomic biomarkers, meaning a test result is either required or recommended before prescribing.
Some of these are purely genetic. The drug adagrasib, for example, is approved specifically for non-small cell lung cancers with KRAS mutations. Olaparib requires confirmation of BRCA1 or BRCA2 mutations before it can be prescribed for ovarian cancer. Others are protein-based: a cancer might be tested for hormone receptor status (a protein biomarker) to determine whether drugs like abemaciclib will work. In practice, a comprehensive biomarker panel for a cancer patient often includes both genetic sequencing and protein-level analysis in a single report.
These tests are sometimes called companion diagnostics because they’re paired with a specific treatment. The FDA maintains a list of approved companion diagnostic devices, and the results can determine whether you’re eligible for a targeted therapy or immunotherapy that wouldn’t help patients whose tumors lack that particular feature.
Biomarker Testing Beyond Cancer
Outside of oncology, biomarker testing leans more heavily on proteins, enzymes, and other non-genetic markers. Cardiac troponin levels are the gold standard for detecting heart muscle injury. Natriuretic peptides (often listed as BNP on lab results) help diagnose heart failure and predict long-term cardiovascular problems in people without symptoms. Galectin-3 levels can help predict mortality risk in patients with decompensated heart failure.
In the overlap between cardiology and cancer care, biomarkers play a dual role. Some cancer treatments can damage the heart, so doctors monitor troponin and natriuretic peptide levels during chemotherapy to catch cardiac toxicity early, ideally before irreversible damage occurs. If levels rise, the care team can adjust the treatment plan or add protective measures while still continuing cancer therapy. These are classic non-genetic biomarkers being used alongside genetic tumor profiling in the same patient.
How Samples Are Collected
The method depends on what’s being measured. A simple blood draw can reveal enzyme levels, protein concentrations, and circulating tumor DNA. For cancer-specific genetic testing, there are two main routes.
A tissue biopsy takes a small core of the tumor itself. This provides the most detailed picture, including the ability to classify a cancer into specific subtypes that carry different prognoses. A liquid biopsy, on the other hand, analyzes tumor DNA, circulating tumor cells, and tiny cellular packages called extracellular vesicles from a standard blood sample. Liquid biopsies are less invasive and can capture genetic information from tumors that are hard to reach with a needle, though tissue biopsies still provide more comprehensive data in many cases.
For non-genetic biomarkers like troponin or liver enzymes, a routine blood test is all that’s needed.
Insurance Coverage Is Still Catching Up
One of the biggest practical barriers to biomarker testing is inconsistent insurance coverage. Medicare expanded access to comprehensive biomarker testing and next-generation sequencing (a technology that reads large stretches of DNA at once) through national coverage decisions in 2020 and 2022. Private insurers, however, aren’t bound by those same rules, and Medicaid coverage varies dramatically by state.
Several states have passed laws to close this gap. Arizona, California, Illinois, Louisiana, and Rhode Island now mandate that state-regulated health plans cover biomarker testing when it’s supported by medical evidence. Illinois requires coverage for biomarker testing related to diagnosis, treatment, management, or monitoring of any medical condition, not just cancer. California went a step further by prohibiting prior authorization requirements for biomarker testing in patients with advanced Stage III or IV cancer.
Even where coverage exists, high out-of-pocket costs and prior authorization requirements remain hurdles. If you’re facing biomarker or genetic testing, checking your specific plan’s coverage policy before the test is ordered can prevent surprise bills. Many labs and pharmaceutical companies also offer financial assistance programs for patients whose testing is tied to a targeted therapy.
A Quick Way to Think About It
If someone orders “genetic testing,” they’re looking at your DNA or your tumor’s DNA for specific mutations or gene variants. If someone orders “biomarker testing,” they might be doing that plus measuring proteins, enzymes, hormone receptors, or other molecular signals. Every genetic test is a biomarker test, but not every biomarker test is genetic. In cancer care especially, the two are often bundled together into a single comprehensive panel, which is why the terms get used interchangeably even though they technically aren’t the same.