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Cancer Markers

Cancer markers, or tumor markers, are substances produced by cancer cells or the body in response to cancer, often found in blood, urine, stool, or tissue. They can be classified into various types, including oncofetal antigens, hormones, enzymes, glycoproteins, and receptors, each associated with specific cancers. While useful for diagnosis, prognosis, and monitoring therapy, tumor markers have limitations such as lack of specificity and sensitivity, and are best used in conjunction with other diagnostic methods.

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16 views3 pages

Cancer Markers

Cancer markers, or tumor markers, are substances produced by cancer cells or the body in response to cancer, often found in blood, urine, stool, or tissue. They can be classified into various types, including oncofetal antigens, hormones, enzymes, glycoproteins, and receptors, each associated with specific cancers. While useful for diagnosis, prognosis, and monitoring therapy, tumor markers have limitations such as lack of specificity and sensitivity, and are best used in conjunction with other diagnostic methods.

Uploaded by

Rajan Giri
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© © All Rights Reserved
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What Are Cancer Markers?

Cancer markers, also known as tumor markers, are substances produced by cancer cells or by
the body in response to cancer. These substances are often proteins and may be found in the
blood, urine, stool, or tissue of some patients with cancer.

Types of Tumor Markers


1. Oncofetal Antigens

Produced during fetal development but reappear in cancer.

• Alpha-fetoprotein (AFP) – liver cancer, germ cell tumors


• Carcinoembryonic antigen (CEA) – colorectal, pancreatic, breast, gastric cancers

2. Hormones

Some tumors produce ectopic hormones.

• hCG (human chorionic gonadotropin) – choriocarcinoma, testicular cancer


• Calcitonin – medullary thyroid carcinoma

3. Enzymes

Produced in higher quantities by tumor cells.

• Prostatic acid phosphatase (PAP) – prostate cancer


• Neuron-specific enolase (NSE) – neuroendocrine tumors, small cell lung cancer

4. Glycoproteins

Altered glycoproteins shed by tumor cells.

• CA-125 – ovarian cancer


• CA 19-9 – pancreatic cancer
• CA 15-3 / CA 27.29 – breast cancer
5. Receptors & Oncoproteins

• HER2/neu – breast cancer


• Estrogen/Progesterone receptors (ER/PR) – breast cancer
• BCR-ABL fusion gene – chronic myeloid leukemia (CML)

Common Tumor Markers Table


Marker Associated Cancer(s) Sample Normal Range (approx.)
AFP Liver, testicular, ovarian Blood < 10 ng/mL
Colorectal, pancreatic, gastric,
CEA Blood < 3 ng/mL (non-smokers)
lung
Choriocarcinoma, germ cell
hCG Blood/Urine < 5 mIU/mL
tumors
PSA Prostate Blood < 4 ng/mL
CA-125 Ovarian Blood < 35 U/mL
CA 19-9 Pancreatic, biliary Blood < 37 U/mL
CA 15-3 Breast Blood < 30 U/mL
< 10 pg/mL (men), < 5 pg/mL
Calcitonin Medullary thyroid Blood
(women)
NSE Small cell lung cancer Blood < 16 ng/mL
BCR- Blood/Bone
Chronic myeloid leukemia Detected via PCR/FISH
ABL marrow

Clinical Uses of Tumor Markers


Purpose Explanation
Rarely used alone due to low sensitivity/specificity. PSA is an
Screening
exception.
Diagnosis Used in combination with other tests and imaging.
Prognosis High levels may indicate worse prognosis (e.g., AFP in liver cancer).
Monitoring therapy Decrease suggests response to treatment.
Detection of
Rising levels post-treatment may indicate relapse.
recurrence
Limitations of Tumor Markers
• Lack of specificity – levels may increase in benign conditions (e.g., CA-125 in
endometriosis).
• Lack of sensitivity – not all cancers secrete markers (e.g., early-stage cancers).
• False positives/negatives – due to non-cancerous conditions or assay variability.
• Best used with imaging and biopsy, not as a sole diagnostic tool.

Advanced Techniques for Detection


• Immunoassays (ELISA, RIA) – for quantifying serum markers.
• Molecular methods (PCR, FISH) – for genetic markers like BCR-ABL.
• Flow cytometry – for leukemia/lymphoma markers (e.g., CD markers).
• Next-gen sequencing (NGS) – detects circulating tumor DNA (ctDNA).

Interpretation Tips
• Always correlate marker values with clinical picture.
• Look for trends, not isolated values (e.g., serial PSA measurements).
• Use reference ranges specific to method and population.

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