Mostly in protein in nature and they are by-products of cancer cells (also by normal cells) of the body in response to cancer.

Only a handful of tumor markers are commonly used by most doctors

Some newer tumor markers help to assess the severity of the cancer, or the response of the cancer to certain drugs.

It is also used to detect recurrent cancer.

Carbohydrate Antigen 15-3 Carbohydrate Antigen 72-4 Estrogen/progesterone receptors Neuron-Specific Enolase Prostate-specific antigen Calcitonin

CA 15-3 290,000 mol. wt. cell surface antigen from

human breast carcinoma Tumor type – Breast carcinoma It is identified by 2 Abs: DF3 and 115DB Detection of <10% in patients with early

disease and 70% in patients with advanced disease

It can be elevated in benign breast conditions and hepatitis

Methods of Assay: ICMA, IEMA and IRMA

CA 72-4 GIT tumor-associated antigen Tumor types – Gastric carcinoma,

colorectal carcinoma, lung carcinoma It is a newer test being studied in

ovarian and pancreatic cancer Methods of Assay: ICMA, IEMA and

IRMA

Intracellular receptor mediating estrogen action

Tumor type – tumor tissue marker of hormone responsiveness

Breast tumor sample (not blood samples) from patients with breast cancer are tested for these markers

Method of Assay: IEMA

NSE It is responsible for the conversion of 2-

phosphoglycerate to phosphoenol pyruvate.

Tumor types: neuroendocrine tumors, including small cell lung cancer (SCLC), neuroblastoma and medullary carcinoma of the thyroid

It is not used as a screening test It is more useful in follow-up of patients

with SCLC and neuroblastoma

PSA 33 kilodalton glycoprotein consisting of

240 amino acids. It is a kallikrein serine protease that may

be identical to the protein found in semen. Tumor type: prostate cancer It is specific for prostate tissue but nor for

prostate cancer It can be elevated in patients with benign

prostatic hyperplasia, elderly men and those with larger prostate.

32 residue polypeptide, a hormone secreted by parafollicular C cells of thyroid.

Tumor type: Medullary Thyroid carnicoma

MTC is inherited and can be detected at earliest stages in family members at risk.

Method of Assay: RIA, IEMA and IRMA