# Tumour marker

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

## TL;DR

A substance, usually a protein, that a tumour releases into the blood in measurable amounts. Rising or falling levels track whether the cancer is growing or responding, though they are rarely good enough for diagnosis on their own.

## Summary

Classic tumour markers are PSA (prostate), CA-125 (ovarian), CEA (colorectal), CA 19-9 (pancreatic), AFP (liver, germ cell), beta-hCG (germ cell) and LDH (a general marker of tumour bulk); most are also made by normal tissue or raised by benign conditions, so they lack the specificity to diagnose cancer and mostly serve to monitor known disease. PSA screening is the well-known exception and the standing example of the trade-off between finding cancers early and overdiagnosing harmless ones. Circulating tumour DNA is in effect a new generation of tumour marker, more specific because it carries the tumour's own mutations.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: tumour markers; tumor marker; tumor markers; serum marker; serum markers; blood marker; blood markers; PSA; CA-125; CA125; CEA; CA 19-9; CA19-9; AFP; LDH

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Tumor_marker
- Wikipedia: https://en.wikipedia.org/wiki/Tumor_marker

## Connected records

- terms: [Biomarker](https://onco.cc/terms/biomarker/), [Circulating tumour DNA (ctDNA)](https://onco.cc/terms/ctdna/), [Early detection](https://onco.cc/terms/early-detection-term/), [Progression](https://onco.cc/terms/progression/), [Screening](https://onco.cc/terms/screening/)
- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Hepatocellular carcinoma](https://onco.cc/cancers/hcc/), [Ovarian cancer](https://onco.cc/cancers/ovarian/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- technologies: [AFP, hCG and LDH in germ cell tumours (IGCCCG risk groups)](https://onco.cc/technologies/germ-cell-tumour-markers/), [CEA surveillance after colorectal cancer surgery](https://onco.cc/technologies/cea-surveillance-colorectal/), [Liquid biopsy (ctDNA)](https://onco.cc/technologies/liquid-biopsy/), [Serum tumour markers: proper use and misuse](https://onco.cc/technologies/serum-tumour-markers/), [Thyroglobulin, calcitonin and CEA in thyroid cancer follow-up](https://onco.cc/technologies/thyroid-cancer-markers/)

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