Tumour markers: serum and tissue, and what each one is for !
- Topic
Markers are molecules that point to a cancer: some are measured in blood to follow treatment, others are stained in the biopsy to name the tumour.
Updated 2026-11-01
What it is
Tumour markers come in two families. Tissue markers are detected in the biopsy, mostly by immunohistochemistry, and tell the pathologist what the tumour is, where it came from and which targeted treatment may work. Serum markers are measured in blood and are used mainly to support a diagnosis, estimate prognosis and follow response and relapse; almost none is good enough to diagnose or screen on its own. The biochemistry of serum markers is covered in Biochemistry; this page links each marker to its tumour and its use.
Key facts
- Immunohistochemistry is decisive for undifferentiated tumours and for carcinoma of unknown primary.
- Intermediate filaments point to the cell family: cytokeratin epithelial, vimentin mesenchymal, desmin muscle, GFAP glial.
- Predictive markers (ER, HER2, PD-L1, KIT) choose treatments; prognostic markers (Ki-67) estimate behaviour.
- Serum markers also rise in benign conditions: CEA in smokers and inflammation, CA-125 in endometriosis and pregnancy, AFP in hepatitis, PSA in prostatitis and benign hyperplasia.
Markers to know: where they are measured and what they are for
| Marker | Where | Tumour | Main use |
|---|---|---|---|
| Cytokeratins | Tissue | Carcinomas (epithelial) | Shows the tumour is epithelial |
| CD45 (leukocyte common antigen), CD20, CD3 | Tissue | Lymphomas (B or T) | Identifies a lymphoid tumour and its lineage |
| S-100, SOX10, HMB-45, Melan-A | Tissue | Melanoma | Confirms melanocytic origin |
| Chromogranin, synaptophysin | Tissue | Neuroendocrine tumours (carcinoid, small cell) | Confirms neuroendocrine differentiation |
| TTF-1; CDX2 | Tissue | Lung adenocarcinoma and thyroid; intestinal adenocarcinoma | Points to the primary site in a metastasis |
| CD117 (KIT), DOG1 | Tissue | Gastrointestinal stromal tumour | Diagnosis and choice of KIT inhibitor |
| ER, PR, HER2 | Tissue | Breast carcinoma | Predict response to hormone or anti-HER2 therapy |
| AFP | Serum | Hepatocellular carcinoma, yolk sac tumour | Diagnosis support and follow-up; excludes pure seminoma when raised |
| β-hCG | Serum | Choriocarcinoma, molar pregnancy, testicular germ cell tumours | Diagnosis and follow-up |
| PSA | Serum | Prostate carcinoma | Follow-up after treatment; screening only after shared decision |
| CEA | Serum | Colorectal and other adenocarcinomas | Follow-up for recurrence; not for diagnosis |
| CA-125; CA 19-9 | Serum | Epithelial ovarian carcinoma; pancreatic and biliary carcinoma | Follow-up of response and relapse |
| Calcitonin | Serum | Medullary thyroid carcinoma | Diagnosis support and follow-up, including MEN 2 families |
| Monoclonal protein (M protein), free light chains | Serum and urine | Multiple myeloma | Diagnosis and follow-up |
Markers
- Cytokeratin
- Vimentin
- Desmin
- CD45
- S-100
- Chromogranin
- TTF-1
- CD117
- ER/PR/HER2
- Ki-67
- AFP
- β-hCG
- PSA
- CEA
- CA-125
- CA 19-9
- Calcitonin
Clinical notes
- Testicular tumours: AFP, β-hCG and LDH are measured before orchiectomy; a raised AFP rules out a pure seminoma.
- A serum marker is most useful when compared with the same patient's previous value, in the same laboratory.
- A normal marker does not exclude cancer and a raised one does not prove it; the diagnosis rests on the biopsy.
- A metastasis of unknown origin is studied with a panel of tissue markers to find the primary site.
Test yourself
Think of the answer, then tap the question to see it.
What is the main clinical use of most serum tumour markers?
Following response to treatment and detecting relapse, by comparing values over time; they are not reliable for screening or diagnosis on their own.
A testicular tumour with a raised AFP cannot be which type?
A pure seminoma; a raised AFP points to a non-seminomatous component such as yolk sac tumour.
Which tissue marker shows that an undifferentiated tumour is a carcinoma?
Cytokeratin, an intermediate filament of epithelial cells.
Which serum marker is used in the follow-up of medullary thyroid carcinoma?
Calcitonin (often together with CEA).
Why are ER, PR and HER2 tested in every breast carcinoma?
They are predictive markers: they show whether hormone therapy or anti-HER2 therapy is likely to work.
Related
- Immunohistochemistry: the principle and the markers to know
- Naming tumours: -oma, carcinoma, sarcoma, and the misleading names
- Differentiation and anaplasia: how a tumour cell looks under the microscope
- Molecular pathology: PCR, FISH, sequencing and liquid biopsy
- Grading and staging: what TNM means
- Paraneoplastic syndromes: the table to know
- Biopsy: excisional, incisional, core needle, punch and fine-needle aspiration
Related conditions
- Prostate cancer
- Testicular cancer
- Ovarian cancer
- Hepatocellular carcinoma
- Colorectal cancer
- Pancreatic cancer
- Medullary thyroid carcinoma
- Gestational trophoblastic neoplasia (choriocarcinoma)
- Ovarian germ-cell and sex cord–stromal tumours
- Multiple myeloma
- Breast cancer
- Carcinoma of unknown primary
- Gastrointestinal stromal tumour (GIST)
- Melanoma
Elsewhere in DurgiPedia
- Tumour markers: principles of use
- Prostate-specific antigen (PSA)
- Alpha-fetoprotein (AFP)
- Carcinoembryonic antigen (CEA)
- Lactate dehydrogenase (LDH) as a lab marker
- Plasma proteins and electrophoresis
- Trophoblast and hCG; gestational trophoblastic disease
- Microscopy and stains: H&E, PAS, trichrome, silver, immunohistochemistry
- CD markers: the table to know
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Tumor Markers (National Cancer Institute (NCI), 2026); Tumor Marker Tests: MedlinePlus Medical Test (MedlinePlus, US National Library of Medicine, 2026); Testicular Cancer (StatPearls (NCBI Bookshelf), 2024).
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