In the past, researchers observed that some cancers (malignant tumours) produce certain proteins such as Alpha Feto Protein (AFP) and Carcino-Embryonic Antigen (CEA), which are similar to those produced by the embryonic cells. These specific proteins were given the name of “Tumour Markers” because these were considered as telltale marks of the tumours. Later, it was observed that the cancerous cells also produce many other biochemicals including specific antigens, cytoplasmic proteins, enzymes and hormones. Tumour markers can now be defined as the biochemical indicators of cancer. These are used to confirm the diagnosis and to determine response of the therapy. Tumour markers also indicate relapse or recurrence of cancer. These can be used in mass cancer screening programmes. The tumour markers are estimated in the plasma and other body fluids.
Alpha Feto Protein (AFP) is normally produced by the foetal liver. The elevated plasma level of AFP in an adult indicates the presence of carcinoma of the liver. It is also raised in cancers of testis, stomach, pancreas, lung or the ovary.
Carcino-Embryonic Antigen (CEA) is another protein that is produced by cancerous cells of the large intestines, liver, stomach, pancreas, melanoma, lymphoma, cervix, bladder, kidney, thyroid and the ovary. CEA is also produced by some of the breast and lung cancers.
Prostate Specific Antigen (PSA) and Prostatic Acid Phosphatase (PAP) are produced by cancerous cells of the prostate. These tumour markers can be used to detect prostate cancer.
Immunoglobulins are tumour markers for multiple myeloma. Multiple myeloma patients were found to excrete an abnormal protein in their urine. This protein was first detected by Henry Bence-Jones at Guy’s hospital in London in 1847 and is named after him. Estimation of the Bence-Jones protein is still used in diagnosing multiple myeloma.
CA 125 is a tumour marker for ovarian cancer. It is also used to detect many other cancers including those of the uterus, cervix, lung, digestive tract, pancreas, liver, colon and the breast.
CA 19-9 is a tumour marker for colorectal and pancreatic cancer. It is also used to detect carcinoma of the stomach and the bile duct.
CA 15-3 is a tumour marker for breast cancer. It is also used to detect cancers of the ovary, lung and the prostate.
CA 27-29 is a tumour marker for breast cancer. It is also used to detect cancers of the colon, stomach, kidney, ovary, lung, pancreas and the liver.
CA 72-4 is a tumour marker for stomach cancer.
Human Chorionic Gonadotrophin is a tumour marker for trophoblastic tumours and non-seminomatous testicular tumours.
Neuron Specific Enolase is a tumour marker for the small cell lung cancer and the neuroblastoma.
Pancreatic Oncofetal Antigen (POA) is a tumour marker for pancreatic cancer.
Lactate Dehydrogenase (LDH) is an enzyme found in blood, which is normally produced by the RBCs, liver, brain and some other tissues of the body. Higher levels of LDH indicate the possible presence of the non-Hodgkin’s lymphoma, Ewing’s sarcoma, leukaemia and testicular cancer.
5-Hydoxy Indole Acetic Acid (5-HIAA) is tumour marker for carcinoid syndrome.
Catecholamines are tumour markers for pheochromocytoma.
Urinary Steroids are tumour markers for the adrenal carcinoma and the para neoplastic Cushing’s syndrome.
Calcitonin is a tumour marker for the medullary cancer of thyroid, myeloma and the multiple endocrine neoplasia.
Thyroglobulins are tumour markers for recurrence of metastases of the thyroid cancer.
Antimalignin Antibody Screen (AMAS) is a less specific tumour marker that simply indicates the presence of a cancer in the body.