PSA tests for prostate cancer screening

The PSA test is currently the only screening test for prostate cancer that has been studied in large trials. In Germany, PSA tests are not covered by public health insurers. Many doctors offer the test as an individual health care service (in German: individuelle Gesundheitsleistungen, or IGeL for short), which you have to pay for yourself. The test costs between 25 and 35 euros. Because it involves a consultation and other related examinations, it often ends up costing around 60 euros in total. The combination with magnetic resonance imaging (MRI) of the prostate is also not normally covered by public health insurance.

The test is used to find the amount of prostate-specific antigen (PSA) in the blood. PSA is a protein that is made in the prostate gland and released into the fluid that carries sperm (called semen). PSA makes this fluid more watery so it is easier for sperm to swim in it.

To determine your PSA level, a blood sample is taken from a vein in your arm at the doctor’s practice and sent to a laboratory. It can take a few days to get the test results back. The amount of PSA in the blood is measured in nanograms per milliliter of blood (ng/ml).

Because the prostate gland has a very good blood supply, small amounts of PSA constantly pass into the bloodstream. A PSA value below 3 ng/ml is considered normal, but there is a big gray area.

High PSA levels can be a sign of prostate cancer, but may also be caused by many other conditions. The reason: If the prostate gland changes or is irritated, a little more PSA is automatically released into the bloodstream. So doctors recommend repeating the PSA test within 3 months if the value is 3 ng/ml or higher. It also makes sense to consider the PSA value together with risk factors like age, medical history, family history, and other test results.

The PSA value may be high in the following situations, for example:

• A benign enlarged prostate (benign prostatic hyperplasia)
• Pressure exerted on the prostate, for example after riding a bicycle, or after examining the prostate gland by feeling it with a finger (palpation) or doing an ultrasound scan
• After ejaculation
• Inflammation of the prostate gland (prostatitis)

It is a good idea to let the doctor know if any of the above have recently occurred so that the test results can be interpreted correctly or the test can be postponed.

But normal PSA levels do not definitely rule out cancer, either: In rare cases, men have normal PSA levels despite having prostate cancer.

But if the PSA level is very high, for example over 10 ng/ml, it is probably due to prostate cancer. PSA levels are rarely that high, though.

High PSA levels can be caused by many things, so abnormal test results don't necessarily mean you have cancer. To find out whether the high PSA levels are caused by cancer or something else, medical societies in Germany recommend taking several steps: First, the PSA test is repeated within three months. If the result is abnormal again, more tests are recommended. That includes a urological examination and an assessment of existing risk factors for prostate cancer. Magnetic resonance imaging (MRI) is used to check whether there are any visible tissue changes in the prostate. Only if the MRI result is abnormal will the next step be to take a biopsy.

To take a tissue sample from the prostate, the doctor usually first inserts a probe about the thickness of a finger into the bowel. From there, thin, hollow needles are pushed into the prostate through the wall of the bowel to take several tissue samples. Another option is to pierce the perineum between the testicles and anus. Ultrasound or MRI is used to check that the needles are moved to the right place.

In a systematic biopsy, 10 to 12 samples are usually taken according to a fixed pattern. In a targeted biopsy, the information from all imaging procedures is used to remove tissue just where abnormal areas were found. If a sample is being taken for the first time, the medical societies in Germany recommend having both a systematic and a targeted biopsy.

You are given antibiotics before the procedure in order to prevent infection. A local anesthetic helps against the pain.

Men often have visible blood in their urine or sperm for several days after the biopsy. They may also have temporary problems when urinating or temporary erection problems.

About 2 out of 100 men who have this kind of biopsy have complications such as an infection. Some men have to go to hospital as a result.

Data from a large European study can be used to see what can be expected from PSA screening. But the results can only be used to get a general idea of what men in Germany can expect from a PSA test. One reason for this is because a different PSA cut-off level was used in this study than the one typically used in Germany.

If 1,000 men between the ages of 55 and 69 regularly have PSA screening tests over a time period of 16 years, the following results can be expected:

About 620 men will have normal results.

• About 380 men will have a high PSA level. Most of these men will then have tissue samples taken from their prostate to check the organ for cancer cells.
• In about 250 of these men, the biopsy will not find any prostate cancer. The PSA test will have been a false alarm.
• In about 130 men with abnormal PSA levels, cancerous cells will be found. Depending on how large and aggressive the cancer is, various treatments may be considered: common ones include "active surveillance," radiotherapy or surgery.
• Up to 60 of these men would never have noticed that they have prostate cancer – and it would never have caused any problems.

• Advantage: For every 1,000 men who take part in PSA screening, about 3 of them will be prevented from getting metastatic tumors and dying of prostate cancer.
• Disadvantage: But the test will also detect tumors and cell changes that would never have caused any problems. This kind of "overdiagnosis" occurs in about 60 out of 1,000 men who take part in this screening program, and they may receive unnecessary treatment as a result. The disadvantage of PSA screening is presumably less if an MRI examination is carried out before the biopsy – as recommended by German medical societies.

The following illustration shows the pros and cons of PSA screening at a glance.

As mentioned above, these numbers are estimates. That's partly because different PSA cut-off levels are recommended in Germany. Also, the men in the study were observed for 16 years on average afterwards. A longer observation period could lead to different results.

PSA tests can prevent some men from dying of prostate cancer. In other men, this screening test causes harm overall because it can lead to overdiagnosis – and unnecessary cancer treatment. So it's worth carefully considering the pros and cons of this screening test before deciding whether or not to have it. The advantages and disadvantages are summarized in the following table.

When making a decision, it's important to remember that some of the potential disadvantages of unnecessary cancer treatment occur straight after having the treatment. These include incontinence and erection problems. The potential benefits of screening usually only become apparent years later, though.

Important: You should decide for yourself whether or not you would like to have a PSA test to screen for prostate cancer. You can take your time to decide whether you want to take part or not. Nobody should feel pressured into having this screening test.