# Biomarker

Source: https://onco.cc/terms/biomarker/  
OnCo record `biomarker` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Anything measurable in the body or tumour that tells you something useful: what kind of cancer it is, how it is likely to behave, or which drug is likely to work.

## Summary

Biomarkers come in three main flavours: diagnostic (what is this?), prognostic (how will it behave regardless of treatment?) and predictive (will this particular treatment work?); ER, PD-L1, HER2, EGFR mutations and MSI are predictive biomarkers with drugs attached to them, PSA and CA-125 are tumour markers used for monitoring, and Ki-67 is prognostic. Predictive biomarkers underpin precision oncology, letting trials enrol only patients likely to benefit and sparing others a useless drug, and a test validated for this purpose becomes a companion diagnostic. Many biomarkers remain imperfect, PD-L1 most famously, and validating and standardising them is one of the field's chronic bottlenecks.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: biomarkers; marker; markers; molecular marker; molecular markers; predictive biomarker; predictive biomarkers; prognostic biomarker; prognostic biomarkers; biomarker-positive; biomarker-negative; biomarker-selected; biomarker-driven; biomarker-defined

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Biomarker_(medicine)
- Wikipedia: https://en.wikipedia.org/wiki/Biomarker_(medicine)

## Connected records

- terms: [Actionable genomic biomarkers](https://onco.cc/terms/cancer-drivers-vs-actionable/), [Analytical versus clinical validation](https://onco.cc/terms/analytical-vs-clinical-validation/), [Biopsy](https://onco.cc/terms/biopsy/), [Circulating tumour DNA (ctDNA)](https://onco.cc/terms/ctdna/), [Companion diagnostic](https://onco.cc/terms/companion-diagnostic-term/), [Enrichment and biomarker-stratified designs](https://onco.cc/terms/biomarker-stratified-design/), [Gene expression](https://onco.cc/terms/gene-expression/), [Genomic profiling](https://onco.cc/terms/genomic-profiling/), [Immunohistochemistry (IHC)](https://onco.cc/terms/ihc/), [Immunotherapy response and its prediction](https://onco.cc/terms/immunotherapy-response/), [Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)](https://onco.cc/terms/msi/), [Overexpression](https://onco.cc/terms/overexpression/), [Prognosis](https://onco.cc/terms/prognosis/), [ROC-AUC, PR-AUC and time-dependent AUC](https://onco.cc/terms/roc-auc/), [Targeted therapy](https://onco.cc/terms/targeted-therapy-term/), [Tumour marker](https://onco.cc/terms/tumour-marker/), [Tumour mutational burden (TMB)](https://onco.cc/terms/tmb/)
- technologies: [CEA surveillance after colorectal cancer surgery](https://onco.cc/technologies/cea-surveillance-colorectal/), [Companion diagnostics](https://onco.cc/technologies/companion-diagnostic/), [Comprehensive genomic profiling](https://onco.cc/technologies/cgp/), [Histopathology & immunohistochemistry](https://onco.cc/technologies/histopathology-ihc/), [Serum tumour markers: proper use and misuse](https://onco.cc/technologies/serum-tumour-markers/)
- journals: [Cancer biomarkers](https://onco.cc/journals/cancer-biomarkers/), [Journal for ImmunoTherapy of Cancer](https://onco.cc/journals/jitc/), [The International journal of biological markers](https://onco.cc/journals/international-journal-of-biological-markers/), [Tumour biology](https://onco.cc/journals/tumour-biology/), [World journal of surgical oncology](https://onco.cc/journals/world-journal-of-surgical-oncology/)
- drugs: [Prosigna (PAM50)](https://onco.cc/drugs/prosigna/)

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