PSA level in prostate cancer
Importance of the PSA value in prostate cancer
Prostate carcinoma is the most common carcinoma in men in Germany. Every eighth man is diagnosed with prostate cancer in his life, which makes it comparable in frequency to breast cancer in women. Since symptoms only appear late, prevention is very important for early detection. In addition to the PCa examination - consisting of anamnesis, general examination and prostate palpation examination (DRE) - the PSA value can also be determined for this early detection. However, due to its low specificity, this is controversially discussed, and so far the value has only had a firm place in the follow-up care of prostate cancer patients.
More on this topic can be found here: Examination of the prostate
What is the PSA value?
The PSA value indicates the concentration of the prostate-specific antigen. As the name suggests, this protein is formed in the prostate, an organ directly below the urinary bladder, which only occurs in men and forms 10-30% of sperm. The production of PSA is stimulated by male sex hormones - the androgens, to which the well-known testosterone belongs.
In general, a PSA value <1 ng / ml is considered harmless, since PSA can also be detected in every man who has a prostate. This is because the PSA belongs to the normal prostate secretion and is therefore physiological in certain quantities. If the values are higher, the value should be checked regularly; if the values are above 4 ng / ml, a more precise diagnosis must be carried out. It should be noted that the PSA value only ever measures the total PSA, which is also referred to as total PSA (tPSA). PSA is not only freely available in the blood; like many substances, it is also bound to other proteins. A distinction is therefore made again between the free fPSA and the bound or complexed cPSA. The following applies:
tPSA = fPSA + cPSA
The free PSA should not be less than 15%, since a low fPSA is suspected of being cancerous. For this reason, the PSA quotient (PSAQ) is often determined today, which is calculated as:
PSAQ = fPSA / tPSA
and thus indicates the proportion of free PSA in the total value.
However, the PSA value alone can only indicate cancer and can never be regarded as conclusive. The reason for this is that the PSA is only produced by the prostate and is therefore organ-specific. However, it is not a tumor marker, but generally indicates a change in the prostate, which does not necessarily have to be malignant.
Read more on the topic PSA value
Why is PSA elevated in prostate cancer?
The PSA is very organ-specific, it is produced exclusively by the prostate. Most changes in the prostate have an elevated PSA level, such as the common benign prostatic hyperplasia (BPH). However, this does not necessarily have to be the case, there are also prostate changes without suspicious PSA values. Prostate cancer is also one of these changes, which in principle can be accompanied by an increase in PSA, but does not have to be. Nevertheless, the higher the PSA value, the more likely it is that the prostate will change.
How useful is the PSA value as a precautionary factor?
Since the PSA value is only specific for the prostate organ, but not for certain diseases such as prostate carcinoma, its determination for cancer prevention is a matter of great controversy. The PSA value is by no means to be regarded as a tumor marker, an increased value is never conclusive for prostate cancer and can only provide an indication or corroborate an existing suspicion. There is also no limit value from which one can definitely assume a malignant event such as cancer; higher values only increase the probability of the presence of a carcinoma of the prostate. The PSA value alone is therefore insufficient for prevention. Men aged 45 and over should have regular preventive examinations for prostate cancer, which initially consists of anamnesis, a general examination and a prostate palpation examination, called DRU. If there is a suspicion or an increased risk of prostate cancer, according to the guideline of the German Cancer Society, the PSA value should be determined. In this case, the provision is also a cash benefit. Depending on the amount, the following recommendations apply for men over 45 years of age with a life expectancy of at least 10 years:
PSA <1 ng / ml: check every 4 years
PSA 1-2 ng / ml: check every 2 years
PSA> 2 ng / ml: check once a year
Ideally, the age of the patient, the prostate volume and the rate of increase of the PSA should always be taken into account. In addition, the PSA quotient can be determined by additionally determining the free PSA; it is calculated as the proportion of fPSA in the tPSA:
PSAQ = fPSA / tPSA.
The proportion of free PSA should be more than 15%, as the fPSA decreases in prostate cancer for reasons that are not yet known. The PSAQ is therefore somewhat more specific for prostate cancer than the pure PSA value, but it is also not conclusive.
How reliable is the PSA value?
As already described, the PSA value is not tumor-specific but only organ-specific; every man with a prostate also has a measurable PSA value.
In everyday clinical practice, the value is usually used as a follow-up and progression marker, so it is more likely to be used when a prostate carcinoma has already been discovered or treated. Since the value is so unspecific, it is less suitable as a screening parameter and should only be used in preventive care in combination with anamnesis, physical examination and DRE.
The following values apply as a rough guide:
<4 ng / ml: prostate cancer very unlikely
4-10 ng / ml: gray area, no precise statement possible
> 10 ng / ml: probability of prostate cancer approx. 40%
In the so-called gray area (4-10 ng / ml), the PSAQ should also be determined.
Which diseases besides prostate cancer increase the PSA level?
In principle, all changes in the prostate can increase the PSA value, but it can be normal for all changes. The value is therefore very unspecific and only provides an indication of a possible change in the prostate. In addition to prostate cancer, these include:
benign prostate hyperplasia (BPH)
prostatitis (inflammation of the prostate)
the prostate infarction
and even excessive cycling
There are, of course, many other causes of elevated PSA levels. In general, every suspicious value should be clarified by a doctor.
Find out more about the PSA value and how to lower it.
How is the prognosis of prostate cancer related to the PSA level?
In general, prostate carcinoma can only be treated curatively and thus cured if it is limited to the organ. As soon as it spreads beyond the organ borders or even forms metastases, the probability of survival drops rapidly.
The level of the PSA value plays a subordinate role in estimating the prognosis and can never make a sole or absolute statement. Estimating the individual prognosis is very difficult anyway, as it depends on many factors.
One of the most important parameters here is the histological finding, which is evaluated with the Gleason score.
Other parameters are above all the age of the patient, previous illnesses and general health. The factors are evaluated together using so-called nomograms and can provide an estimate of the prognosis.
However, this should only be left to the treating specialist.
Read more about here treatment and forecast in prostate cancer.
What is the PSA value after removal of the prostate?
After a prostatectomy, i.e. the surgical removal of the prostate, the PSA value is measured at regular intervals. It should drop below the detection limit within 4-6 weeks, since ideally there is no longer any tissue that could produce the PSA.
If this is not the case or if the value rises again above 0.2 ng / ml after an initial drop, this indicates a so-called biochemical relapse, also known as “PSA progress”. In this case, a urologist should be consulted urgently.
What does it mean if the PSA value rises again?
As already mentioned, the PSA value is not necessarily suitable for the early detection of prostate carcinomas. However, it looks completely different in the follow-up care: After the treatment of the tumor, regular checks must be carried out, during which, in addition to a palpation examination (DRE), the PSA value is determined. A relapse, i.e. a recurrence of the prostate carcinoma, can be detected very early by means of the PSA value. If the PSA value rises above a certain limit value in the follow-up, one speaks of a biochemical relapse. In addition to a local recurrence, the PSA can also be caused by metastases that have not yet been discovered or treated. In any case, an increase in the PSA value in the follow-up care after the therapy has been completed requires a detailed investigation.
However, even after radiation therapy for prostate cancer, the PSA value often increases after 1 to 5 years. The reasons for this are still unknown today.