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and Other Diagnostic Acronyms

Last Revised May 14, 1997
[Note there may have been developments since this was written.]

Introduction | PSA | PSA II | PSAV | PSAD | DRE | RTPCR | PAP | TRUS


An "acronym" is an abbreviation usually made up from the first letters of the words it is being used to abbreviate. Thus, for example, FBI is an acronym for Federal Bureau of Investigation and NFL is an acronym for the National Football League.

Medicine is full of acronyms. In fact there are even books which list medical acronyms so that you can look them up if you don't know what a particular acronym stands for! Acronyms are also common in the diagnosis and treatment of prostate cancer, so we thought it would be a good idea if we listed some of the most common ones here and gave a brief explanation. If you or one of your family or friends has or thinks he might have prostate cancer, chances are you will hear most of these acronyms in the future.


PSA stands for prostate specific antigen. The PSA test or prostate specific antigen test has revolutionized the detection of prostate cancer and monitoring of the effects of treatment since the mid 1980s. On its own, it is very probably responsible for the accurate diagnosis of prostate cancer in millions of men worldwide. Equally, it is probably the single most important factor in the unnecessary treatment of some men who might well have died of old age or many other reasons without the slightest reason to suspect that prostate cancer was anything for them to worry about -- which they did but shouldn't have!

The PSA test is a classic case of science providing us with information which we do not always know how to use to our best advantage. If you have to talk to your doctor about the results of PSA tests (your own or a family member's), be sure that you listen very carefully, ask a lot of questions, and do your very best to be patient with the doctor because it may be impossible -- or at least very hard -- for him or her to give you the answers you are looking for!

A PSA test tells your doctor the level of prostate specific antigen in your blood, just like a cholesterol test can tell your doctor the levels of cholesterol in your blood. Using the most common type of PSA test currently available in the USA, the average, normal, healthy, 50-year-old male is generally believed to have a PSA of less than 4.0 nanograms per milliliter of blood (4.0 ng/ml). There are a number of reasons why any one person's PSA could be higher than that. Prostate cancer is just one of those reasons. What the results of PSA tests do NOT do is tell you and your doctor how to act on the results of those tests! For more information about the value and importance of PSA and PSA testing, see

You may also want to review the prostate cancer testing advice and consent materials used by one group of physicians in helping patients to decide whether they wish to have a PSA test for prostate cancer.


The PSA II or free/total PSA test is a new type of PSA test that can be used to help the physician discriminate between patients with relatively low standard PSA levels (say 2.5-10.0 ng/ml) who are at greatest risk of having prostate cancer (and therefore need a prostate biopsy), and those patients who are more likely to have benign prostatic hyperplasia (BPH).

Basically, the PSA II test measures the amount of PSA that is free in the blood stream, and compares it to the total free and bound PSA found in the blood (including the PSA that is "bound" to other products in the blood). The lower the ratio of free to total PSA, the higher the likelihood that the patient has prostate cancer as opposed to benign prostatic hyperplasia. Patients with a very low ratio (e.g., 0.05 or 5%) are at very high risk for prostate cancer.

The PSA II test allows the urologist to give a non-invasive test to patients with PSA values between 2.5 and 10.0 ng/ml who may be at risk for prostate cancer and to determine the degree of that risk before deciding whether to give the patient a biopsy.


PSAV stands for PSA velocity, which is best described as the speed at which a series of PSA values increases (or decreases) in value. Some physicians believe that use of PSA velocity allows them to tell more about the way prostate cancer may be developing in individual patients. Let's say it is January 1995 and Harry, who is 68 years old and otherwise in excellent health, has a PSA test. The doctor tells him his PSA value is 4.2 ng/ml, and it's nothing to worry about but the doctor suggests to Harry that he comes back for another test a year later. In January 1996, Harry comes back for his next test. The value is 4.4 ng/ml. Again, the doctor says its nothing to worry about but to come again the next year. In January 1997, back comes Harry for the third time. This year the value is 4.6 ng/ml. Each year for two years, Harry's PSA value has increased by 0.2 ng/ml. We say that his PSA velocity is 0.2 nanograms per milliliter of blood per year (0.2 ng/ml/yr).


PSAD stands for PSA density. PSA density is a measure of the concentration of PSA in a man's prostate. It depends upon the value of his PSA and the size of his prostate. Again, like PSA velocity, some specialists believe that PSA density can be useful in telling how to treat individual patients.

Let's say that Bill has a PSA value of 5.1 ng/ml. When his physician measures the volume of Bill's prostate, the doctor calculates that it is about 50 cubic centimeters (50 cc), which is about the same size as a large walnut. Then Bill's PSA density is 5.1 divided by 50 = 0.102 ng/ml/cc.


DRE stands for digital rectal examination. In a digital rectal examination the physician inserts his finger into the rectum in order to be able to feel the size, shape, and texture of the prostate and other nearby organs. In classical medicine, before the availability of the modern wonders of science, the digital rectal examination was the only way a physician could tell if there was a possible disorder of the prostate, short of cutting you open and looking.

Over the years, highly experienced physicians became relatively good at using digital rectal examinations to tell whether patients had clinically important prostate disorders. However, DRE is a "subjective" technique. In other words, the ability to use a DRE well is all about the skill of the physician and his or her ability to interpret what he or she feels.

The problem with using DREs to make decisions about what to do with particular patients is that two different, experienced physicians may think that they feel quite different things when they carry out a DRE on the same patient. Neither of these physicians is necessarily right or wrong in what they think. They cannot see what they are feeling and they are doing their best to make wise decisions. Imagine trying to do something similar. You are blindfolded and wearing a pair of plastic gloves. Someone places two pool balls in your hands and tells you the red one has a tiny crack in it. Now, which one is the red ball and which is the other ball? Easy, huh? Well it would be if the crack was big enough, but when it's a really tiny crack?


RTPCR stands for reverse transcriptase polymerase chain reaction. RTPCR testing is only a few years old. It can be used to detect minute amounts of one of the nucleic acids which makes prostate specific antigen. Theoretically, RTPCR is so sensitive that it is capable of finding one piece of PSA nucleic acid in a blood sample containing a million other pieces of nucleic acid of comparable size. This would be wonderful if we could be sure that finding one such piece of nucleic acid absolutely always meant that prostate cancer had escaped from the prostate and was "metastasizing" to other sites in the body. Unfortunately, that isn't the case. A positive reaction to an RTPCR test can occur for all sorts of reasons in a patient who still has clinical prostate cancer confined to the prostate. Life just isn't as simple as we'd like it to be.

RTPCR testing is at best an investigational technique. It is not yet approved or recommended for use in normal clinical practice. However, if you or a friend or relation are involved in a clinical trial of a new form of prostate therapy, RTPCR testing may be a form of testing that is used in that trial as doctors and scientists try to learn more about prostate cancer and which patients most need to be treated with what types of therapy. There is little doubt we will all continue to hear more about RTPCR testing in the future. However, whether it will ever be possible to use RTPCR testing as a diagnostic or prognostic test is open to considerable question.


PAP stands for prostatic acid phosphatase. Just as RTPCR is a very new and experimental test for prostate cancer outside of the prostate, PAP is a much older test which was in very common use before PSA testing became possible. Today, PAP tests are relatively rare. However, there are still reasons why doctors may think a PAP test is valuable for a specific patient. If your doctor tells you you need a PAP test, you should ask ask him or her to explain what the PAP test may be able to tell that can't be learnt from PSA testing or other forms of available test. The commonest reason for use of a PAP test is that it may help to identify a patient with metastatic prostate cancer.


TRUS stands for transrectal ultrasound. TRUS is most commonly used to do two things. The first is to guide the doctor when he or she is carrying out a technique known as a biopsy of the prostate, when small samples of tissue are taken from the prostate in order to make a proper diagnosis. The second is in order to try and establish the volume of the prostate, which is important if the doctor wants to know the PSA density. Specialists may also use TRUS for other reasons in some prostate cancer patients or patients suspected of prostate cancer. However, it has now been generally agreed that TRUS has no particular value in identifying patients with prostate cancer when used on its own or in combination with such techniques as DRE or PSA.

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The content in this section of the Phoenix 5 site was originally developed by CoMed Communications (a Vox Medica company) as part of The Prostate Cancer InfoLink. It is reproduced here with the permission of Vox Medica.

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