Tumour (psa) array

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Intended Use

Evidence Tumour PSA Array is to be used for the in vitro simultaneous quantitative detection of multiple related tumour immunoassays (in parallel) from a single patient sample.

Clinical Significance

The Tumour PSA Array can be run on Evidence, for the screening of prostate cancer. The assaying of tumour markers has become one of the most rapidly growing areas in all laboratory medicine. With the identification of these markers we are getting closer to more efficient and accurate diagnosis and monitoring of different cancers to improve our success in the worldwide fight against cancer.

Principle

The Evidence analyser is a fully automated Biochip Array System. It performs simultaneous quantitative detection of multiple analytes from a single patient sample and therefore carries out sample assays much faster and efficiently than conventional laboratory analysers. The core technology is the Randox Biochip, a 9 mm (2) solid substrate containing an array of discrete test regions. A chemiluminescent immunoassay is employed for the Tumour PSA Array. The light signal generated from each of the test regions on the biochip is detected using state-of-the-art digital imaging technology.

Several different immunoassay based multi-analyte arrays have been developed for use on Evidence. The Evidence PSA tumour Array will successfully quantitatively test for CEA, Total PSA and Free PSA simultaneously.

 

Carcinoembryonic Antigen (CEA) Assay

Intended Use

Evidence has been designed to measure qualitatively or quantitatively tumour associated antigens in serum. This can be used as an aid in monitoring patients for disease progress, response to therapy or for the detection of recurrent or residual disease.

Clinical Significance

CEA (carcino-embryonic antigen), discovered in 1965 by Gold and Freedman, is a cancer antigen produced in response to malignant cells in adults but it is also present during foetal development. This is a high molecular weight non-mucinous glycoprotein secreted by the epithelial cells of the digestive tract, and originally thought to be present in colonic tumours only (1,2). However, it has now been found to occur in raised levels in patients with breast, ovarian, stomach, pancreatic and lung cancers, as well as other non-cancerous diseases (2,3,4).

The CEA test has been shown to be of value in the monitoring of patients with diagnosed malignancies who are undergoing therapy. Elevation of CEA following therapy is indicative of metastatic disease or residual disease. A persistent level of CEA during therapy suggests a poor therapeutic response. While decreases in levels of CEA during therapy is indicative of response to treatment and therefore favourable prognosis.

CEA is the second most common tumour marker in use (2). It can be used in screening, to aid with the early detection of prostate cancer, and in monitoring colorectal, breast, gastric and lung cancer patients post treatment. The discovery of raised CEA levels in the screening process suggests that carcinoma could be present and consequently other diagnostic tests can be performed to increase diagnostic accuracy (2). By combining CEA with other tumour markers the efficacy of the marker can also be improved (5).

In post therapy management, levels of CEA are monitored due to adjustments in marker level indicating the therapeutic success. Observing level of CEA post therapy will reveal any residual disease, remission or relapse (4,5).

Principle

The Evidence CEA assay is a chemiluminescent immunoassay for the detection of CEA in human serum.

REFERENCES

1. Gold P, Freedman SO, Specific carcinoembryonic antigens of the human digestive system, Journal of Exploratory Medicine, 1965; 122: 467-481.

2. Wild D. (ed), The Immunoassay Handbook, second edition, Nature Publishing Group, London, Basingstoke, New York, 2001; 635-663.

3. Maxwell P, Carcinoembryonic antigen: cell adhesion molecule and useful diagnostic marker, British Journal of Biomedical Science, 1999; 56: 209-214.

4. Sell, S. Detection of Cancer by Tumor Markers in the Blood: A View to the Future. Critical Reviews in Oncogenesis, 1993; 4(4): 419-433.

5. Pathak K et al, Carcinoembryonic antigen: an invaluable marker for advanced breast cancer, Journal of Postgraduate Medicine, 1996; 42 (3): 68-71.

 

Total Prostate Specific Antigen (TPSA) Assay

Intended Use

Evidence has been designed to measure quantitatively tumour associated antigens in serum. This can be used for screening as an aid in the initial detection of prostate cancer, as an aid in monitoring patients for disease progress, response to therapy or for the detection of recurrent or residual disease.

Clinical Significance

Prostate specific antigen (PSA) is a 33 KDa glycoprotein member of the glandular kallikrien family of proteins (1). PSA is predominantly manufactured by the prostatic secretory epithelium and the epithelial lining of the periurethral glands and acts as a serine protease to liquefy the seminal coagulum (2).

PSA concentration in the secretions of the normal prostate gland are approximately one million times of that in serum. PSA gains access to the bloodstream by vascular overflow from the prostate gland. PSA is present in serum as both complexed and uncomplexed molecules. The majority of PSA is irreversibly complexed to a 1 -antichymotrypsin (PSA-ACT) (3)and approximately 30% is the enzymatically inactive free PSA.

PSA is not specific for prostate cancer as other conditions such as benign prostatic hyperplasia (BPH) and prostatitis can also cause increased PSA levels (4). Use of the Evidence Total PSA assay in conjunction with the Evidence Free PSA assay may help improve patient diagnosis.

The two monoclonal antibodies used in the Evidence total PSA assay recognise free PSA and complexed PSA on an equimolar basis (5, 6).

Principle

The Evidence TPSA assay is a chemiluminescent immunoassay for the detection of TPSA in human serum.

REFERENCES

1. Clements J., The human kallikrein gene family: a diversity of expression and function, Molecular and Cellular Endocrinology 1994; 99: C1-C6.

2. Pollen J. J. and Dreilinger A., Immuno-histochemical identification of prostatic acid phosphatase and prostate specific antigen in female periurethral glands, Urology, 1984; 223: 303-304

3. Lilja H., Christensson A., Dahlén U., Matikainen, M.T., Nilsson O., Pettersson K. and Lövgren T. Prostate-specific antigen in serum occurs predominantly in complex with a 1 -antichymotrypsin, Clinical Chemistry, 1991; 37: 1618-1625.

4. Partin A. W., Carter H.B., Chan D.W., Epstein J.I., Oesterling J. E., Rock R.C., Weber J.P. and Walsh P. C., Prostate specific antigen in the staging of localised prostatic cancer: influence of tumor differentiation, tumor volume and benign hyperplasia, Journal of Urology, 1990; 143: 747-752

5. Becker C., Wigheden I., Lilja H., Characterization of epitope structure for 53 monoclonal antibodies against prostate-specific antigen, Tumor Biology, 1999; 20 (suppl 1): 13-17.

6. Nilsson O., Anderson I., Peter A., Karlsson B., Characterization of antibodies to prostate-specific antigen, Tumor Biology, 1999; 20 (suppl 1): 43-51.

 

Free Prostate Specific Antigen (FPSA) Assay

Intended Use

Evidence has been designed to measure qualitatively or quantitatively tumour associated antigens in serum. This can be used for screening as an aid in the initial detection of prostate cancer, as an aid in monitoring patients for disease progress, response to therapy or for the detection of recurrent or residual disease.

Clinical Significance

Prostate specific antigen (PSA) is a 33 KDa glycoprotein member of the glandular kallikrien family of proteins (1). PSA is predominantly manufactured by the prostatic epithelium and the epithelial lining of the periurethral glands and acts as a serine protease to liquefy the seminal coagulum (2).

PSA concentration in secretions of the normal prostate gland are approximately one million times that in serum. PSA gains access to the bloodstream by vascular overflow from the prostate gland. PSA is present in serum as both complexed and uncomplexed molecules. The majority of PSA is irreversibly complexed to a 1 -antichymotrypsin (PSA-ACT) (3) and approximately 30% is the enzymatically inactive free PSA.

PSA is not specific for prostate cancer as other conditions such as benign prostatic hyperplasia (BPH) and prostatitis can also cause increased PSA levels (4). It has been shown that the % free PSA is higher in patients with BPH than those with prostate cancer (5). Use of the Evidence free PSA assay in conjunction with the Evidence total PSA assay may help improve patient diagnosis.

Principle

The Evidence FPSA assay is a chemiluminescent immunoassay for the detection of FPSA in human serum.

REFERENCES

1. Clements J., The human kallikrein gene family: a diversity of expression and function, Molecular and Cellular Endocrinology 1994; 99: C1-C6.

2. Pollen J. J. and Dreilinger A., Immuno-histochemical identification of prostatic acid phosphatase and prostate specific antigen in female periurethral glands, Urology, 1984; 223: 303-304

3. Lilja H., Christensson A., Dahlén U., Matikainen, M.T., Nilsson O., Pettersson K. and Lövgren T. Prostate-specific antigen in serum occurs predominantly in complex with a 1 -antichymotrypsin, Clinical Chemistry, 1991; 37: 1618-1625.

4. Partin A. W., Carter H.B., Chan D.W., Epstein J.I., Oesterling J. E., Rock R.C., Weber J.P. and Walsh P. C., Prostate specific antigen in the staging of localised prostatic cancer: influence of tumor differentiation, tumor volume and benign hyperplasia, Journal of Urology, 1990; 143: 747-752.

5. Becker C., Wigheden I., Lilja H., Characterization of epitope structure for 53 monoclonal antibodies against prostate-specific antigen, Tumor Biology, 1999; 20 (suppl 1): 13-17.