223 biomarkers indexed · for reference use
The biomarker reference clinicians can trust.
A clinical reference for patients, physicians, and researchers. Each biomarker explained in plain terms, with the detail depth experts need.
Every entry tagged Established or Emerging — because "promising research" and "standard of care" are not the same thing.
Definition
What is a biomarker?
A biomarker is a measurable substance in the body — a protein, hormone, enzyme, antibody, or genetic marker — that provides a window into what's happening inside a patient's cells.
Biomarkers can be found in blood, urine, tissue, or other body fluids, and each one tells a specific part of a larger story: whether a disease is present, how advanced it is, whether a treatment is working, or whether cancer is likely to respond to a particular drug.
Some biomarkers have been used in medicine for decades — hemoglobin A1c for diabetes, PSA for prostate health, troponin for heart attacks. Others are newer, more specialized tools that have only become part of clinical practice in the last few years, as cancer treatment has shifted toward precision medicine: matching the right drug to the right patient based on the molecular features of their specific disease.
In practice
Why biomarkers matter in clinical practice
Biomarkers do far more than confirm a diagnosis. Across modern medicine, they carry weight at nearly every decision point.
A patient's HER2 or PD-L1 status can determine which cancer drug is likely to work — and which one won't. BRCA1/2 status determines eligibility for an entire class of targeted therapies. In many cancers, testing before treatment isn't optional anymore; it's the standard of care.
Markers like Ki-67 or specific gene mutations help physicians estimate how aggressive a tumor is likely to be — informing how closely a patient needs to be monitored and how intensively they should be treated.
Falling PSA, disappearing circulating tumor DNA, or a shrinking CA-125 level can tell a care team that a treatment is working — often before a scan would show any visible change.
Many cancers are followed after treatment using the same biomarker that helped diagnose them, sometimes detecting a relapse months before symptoms appear.
Genetic biomarkers like BRCA1/2 or Lynch syndrome-associated genes don't just inform one patient's care — they can prompt entire families to pursue genetic counseling and earlier screening.
No single biomarker tells the whole story on its own. In practice they're interpreted together — alongside imaging, symptoms, family history, and clinical judgment — which is exactly why accurate, current reference information matters.
The directory
What's in this directory
Each described in plain terms alongside the clinical detail a physician or researcher needs: what the biomarker is, what it indicates, how it's tested, how it's used to guide treatment, and where the evidence currently stands.
Open the directory →We draw this line deliberately and stay transparent about where each biomarker sits, because conflating early research with standard of care leads patients and clinicians to the wrong conclusions from a lab result.
Who it's for
One reference, three readers
A clear, honest explanation
Researching a diagnosis or a lab result deserves a plain explanation of what a biomarker means — without overstating its certainty or burying it in jargon. Every entry includes a plain-language summary alongside the clinical detail.
A fast, reliable reference
Across an enormous, constantly shifting body of literature, this directory consolidates testing methodology, specimen requirements, treatment implications, and current guideline context in one place — with sourced references for further reading.
A structured view of the field
A structured view of the current landscape — established, emerging, and in time the investigational candidates still working through abstracts and early trials. Knowing where the field stands is the starting point for seeing where it needs to go.
Our aim
Closing a real gap in biomarker information
Reliable biomarker information is scattered across journal articles, conference abstracts, package inserts, and institutional websites — often written for a single audience and rarely kept current. We built this as a single, freely accessible reference that serves patients, clinicians, and scientists with the same underlying information, presented at the level of detail each of them needs.
This work is part of Biomarker.org's broader mission: advancing precision medicine by improving how cancer is detected, understood, and treated — and charting, as clearly and honestly as the evidence allows, where the field is headed next.
Discovering new cancer-specific antigens for the next generation of targeted therapies. Where this directory makes sense of the biomarkers already shaping care, Oncotope works on the ones still to come.
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