PCA3
Encyclopedia
Prostate cancer antigen 3 (PCA3, also referred to as DD3) is a gene which has noncoding
messenger RNA
that is overexpressed
in prostate cancer
. This messenger RNA is useful as a tumor marker
.
level of prostate-specific antigen (PSA), or derived measurements. However, since PSA is prostate
-specific but not cancer
-specific, it is an imperfect biomarker. For example, PSA can increase in older men with benign prostatic hyperplasia
. Several new biomarkers are being investigated to improve the diagnosis of prostate cancer. Some of these can be measured in urine samples, and it is possible that a combination of several urinary biomarkers will replace PSA in the future.
Compared to serum PSA, PCA3 has a lower sensitivity but a higher specificity and a better positive
and negative predictive value
. It is independent of prostate volume, whereas PSA is not. It should be measured in the first portion of urine after prostate massage
with digital rectal examination.
PCA3 has been shown to be useful to predict the presence of malignancy in men undergoing repeat prostate biopsy
. This means that it could be useful clinically for a patient for whom digital rectal examination and PSA suggest possible prostate cancer, but the first prostate biopsy returns a normal result. This occurs in approximately 60% of cases, and on repeat testing, 20-40% have an abnormal biopsy result.
Other uses that are being studied for PCA3 include its correlation with adverse tumor features such as tumor volume, grading (Gleason score
) or extracapsular extension. These studies have so far produced conflicting results.
A commercial kit called the Progensa PCA3 test is marketed by the Californian company Gen-probe
. PCA3 Rights acquired from Diagnocure back in 2003. Royalties of 16% of cumulative sales of PCA3 kit are paid to Diagnocure. Diagnocure is quoted on TSX
as CUR.TO (Canada)
Non-coding RNA
A non-coding RNA is a functional RNA molecule that is not translated into a protein. Less-frequently used synonyms are non-protein-coding RNA , non-messenger RNA and functional RNA . The term small RNA is often used for short bacterial ncRNAs...
messenger RNA
Messenger RNA
Messenger RNA is a molecule of RNA encoding a chemical "blueprint" for a protein product. mRNA is transcribed from a DNA template, and carries coding information to the sites of protein synthesis: the ribosomes. Here, the nucleic acid polymer is translated into a polymer of amino acids: a protein...
that is overexpressed
Gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...
in prostate cancer
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...
. This messenger RNA is useful as a tumor marker
Tumor marker
A tumor marker is a substance found in the blood, urine, or body tissues that can be elevated in cancer, among other tissue types. There are many different tumor markers, each indicative of a particular disease process, and they are used in oncology to help detect the presence of cancer...
.
Use as biomarker
The most frequently used biomarker for prostate cancer today is the serumBlood serum
In blood, the serum is the component that is neither a blood cell nor a clotting factor; it is the blood plasma with the fibrinogens removed...
level of prostate-specific antigen (PSA), or derived measurements. However, since PSA is prostate
Prostate
The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....
-specific but not cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
-specific, it is an imperfect biomarker. For example, PSA can increase in older men with benign prostatic hyperplasia
Benign prostatic hyperplasia
Benign prostatic hyperplasia also known as benign prostatic hypertrophy , benign enlargement of the prostate , and adenofibromyomatous hyperplasia, refers to the increase in size of the prostate....
. Several new biomarkers are being investigated to improve the diagnosis of prostate cancer. Some of these can be measured in urine samples, and it is possible that a combination of several urinary biomarkers will replace PSA in the future.
Compared to serum PSA, PCA3 has a lower sensitivity but a higher specificity and a better positive
Positive predictive value
In statistics and diagnostic testing, the positive predictive value, or precision rate is the proportion of subjects with positive test results who are correctly diagnosed. It is a critical measure of the performance of a diagnostic method, as it reflects the probability that a positive test...
and negative predictive value
Negative predictive value
In statistics and diagnostic testing, the negative predictive value is a summary statistic used to describe the performance of a diagnostic testing procedure. It is defined as the proportion of subjects with a negative test result who are correctly diagnosed. A high NPV means that when the test...
. It is independent of prostate volume, whereas PSA is not. It should be measured in the first portion of urine after prostate massage
Prostate massage
Prostate massage is the massage or stimulation of the male prostate gland for sexual stimulation or medical purposes.The prostate takes part in the sexual response cycle, and is essential for ejaculation...
with digital rectal examination.
PCA3 has been shown to be useful to predict the presence of malignancy in men undergoing repeat prostate biopsy
Prostate biopsy
Prostate biopsy is a procedure in which small samples are removed from a man's prostate gland to be tested for the presence of cancer. It is typically performed when the scores from a PSA blood test rise to a level that is associated with the possible presence of prostate cancer.The procedure,...
. This means that it could be useful clinically for a patient for whom digital rectal examination and PSA suggest possible prostate cancer, but the first prostate biopsy returns a normal result. This occurs in approximately 60% of cases, and on repeat testing, 20-40% have an abnormal biopsy result.
Other uses that are being studied for PCA3 include its correlation with adverse tumor features such as tumor volume, grading (Gleason score
Gleason score
The Gleason Grading system is used to help evaluate the prognosis of men with prostate cancer. Together with other parameters, it is incorporated into a strategy of prostate cancer staging which predicts prognosis and helps guide therapy. A Gleason score is given to prostate cancer based upon its...
) or extracapsular extension. These studies have so far produced conflicting results.
A commercial kit called the Progensa PCA3 test is marketed by the Californian company Gen-probe
Gen-Probe
Gen-Probe is a public biotechnology company based in San Diego, California employing approximately 1,300, and specializing in Clinical Diagnostics, Blood Screening, Transplant Products and Research Products...
. PCA3 Rights acquired from Diagnocure back in 2003. Royalties of 16% of cumulative sales of PCA3 kit are paid to Diagnocure. Diagnocure is quoted on TSX
as CUR.TO (Canada)