Prostate cancer antigen 3 (PCA3, also referred to as DD3) is a gene that expresses a
non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally important types of non-c ...
. PCA3 is only expressed in human prostate tissue, and the gene is highly overexpressed in
prostate cancer
Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that sur ...
.
Because of its restricted expression profile, the PCA3 RNA is useful as a
tumor marker
A tumor marker is a biomarker found in blood, urine, or body tissues that can be elevated by the presence of one or more types of cancer. There are many different tumor markers, each indicative of a particular disease process, and they are used in ...
.
Use as biomarker
The most frequently used
biomarker
In biomedical contexts, a biomarker, or biological marker, is a measurable indicator of some biological state or condition. Biomarkers are often measured and evaluated using blood, urine, or soft tissues to examine normal biological processes, ...
for prostate cancer today is the
serum level of
prostate-specific antigen
Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), P-30 antigen, is a glycoprotein enzyme encoded in humans by the ''KLK3'' gene. PSA is a member of the kallikrein-related peptidase family and is secreted b ...
(PSA), or derived measurements. However, since PSA is
prostate
The prostate is both an Male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, ...
-specific but not
cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
-specific, it is an imperfect biomarker. For example, PSA can increase in older men with
benign prostatic hyperplasia
Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss o ...
. Several new biomarkers are being investigated to improve the diagnosis of prostate cancer. Some of these can be measured in
urine sample
A urine test is any medical test performed on a urine specimen. The analysis of urine is a valuable diagnostic tool because its composition reflects the functioning of many body systems, particularly the kidneys and urinary system, and specimens a ...
s, 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 is a property of positivity and may refer to:
Mathematics and science
* Positive formula, a logical formula not containing negation
* Positive number, a number that is greater than 0
* Plus sign, the sign "+" used to indicate a posit ...
and
negative predictive value
The positive and negative predictive values (PPV and NPV respectively) are the proportions of positive and negative results in statistics and diagnostic tests that are true positive and true negative results, respectively. The PPV and NPV descr ...
.
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 is the massage or stimulation of the male prostate gland for medical purposes or sexual stimulation.
The prostate takes part in the sexual response cycle, and is essential for the production of semen. Due to its proximity to th ...
with
digital rectal examination
Digital rectal examination (DRE; la, palpatio per anum, PPA) is an internal examination of the rectum, performed by a healthcare provider. Prior to a 2018 report from the U.S. Preventive Services Task Force, the DRE was a common and "dreaded" co ...
.
PCA3 has been shown to be useful to predict the presence of malignancy in men undergoing repeat
prostate biopsy
Prostate biopsy is a procedure in which small hollow needle-core samples are removed from a man's prostate gland to be examined for the presence of prostate cancer. It is typically performed when the result from a PSA blood test is high. It may ...
.
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
The Gleason grading system is used to help evaluate the prognosis of men with prostate cancer using samples from a prostate biopsy. Together with other parameters, it is incorporated into a strategy of prostate cancer staging which predicts pr ...
) or extracapsular extension. These studies have so far produced conflicting results.
Society and culture
A commercial kit called the Progensa PCA3 test is marketed by the Californian company
Gen-Probe
Gen-Probe was a company based in San Diego, in California, specializing in clinical diagnostics, blood screening, transplantation products and research products.
The company's molecular diagnostics products were used for diagnosis of infectious ...
. Gen-Probe acquired rights to the PCA3 test from
Diagnocure in 2003. In April 2012,
Hologic
Hologic, Inc. is a medical technology company primarily focused on women’s health; it sells medical devices for diagnostics, surgery, and medical imaging.
History
In late November 2013, activist investor Carl Icahn disclosed a 12.5% stake in t ...
bought Gen-Probe for $3.75 billion by cash.
Discovery
PCA3 was discovered to be highly expressed by prostate cancer cells in 1999.
References
Further reading
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External links
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{{Tumor markers
Non-coding RNA
RNA
Tumor markers