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Limitations of traditional rectal prostate biopsy

Up to now, the diagnosis of suspected prostate cancer consisted of a palpation of the prostate (so-called digital rectal examination, DRU) and the determination of a blood value, the so-called prostate-specific antigen (PSA).

In the case of conspicuous findings, an ultrasound-guided biopsy of the prostate was performed via the rectum. Today, this procedure is increasingly viewed critically. Today, the primary aim is to avoid biopsies. However, if a biopsy is necessary, the tumour should be precisely and reliably targeted by the biopsy. Furthermore, the biopsy must ensure that there are no other tumours in the rest of the prostate. This is of utmost importance for planning a focal therapy. The solution is robot-assisted mpMRI/TRUS fusion and mapping biopsy of the prostate.

Limitations of traditional rectal prostate biopsy

Two tumours are localised in the prostate shown: In the centre of the image above, with a dark centre, an aggressive prostate carcinoma requiring treatment. The image on the left, light blue, shows a prostate cancer that does not require treatment.

Prostate biopsy
Figure 1/4

Prostate biopsy

Both tumours in the prostate are not hit.

Prostate biopsy
Figure 2/4

Prostate biopsy

The low-risk tumour is diagnosed, the aggressive and dangerous tumour is overlooked.

Prostate biopsy
Figure 3/4

Prostate biopsy

The relevant prostate carcinoma is only hit in the periphery and thus its aggressiveness is underestimated.

Prostate biopsy
Figure 4/4

Prostate biopsy

This is how it should be. The prostate carcinoma in need of treatment is targeted.

In order to avoid unnecessary treatment, it is important to distinguish between significant (in need of treatment) and insignificant (not in need of treatment) prostate carcinomas. This subdivision is based, among other things, on the fine-tissue (histological) examination of tissue samples from the prostate, so-called biopsies.

The standard procedure is the systematic transrectal ultrasound-guided biopsy (TRUS). In this procedure, 10-12 biopsy cylinders are taken from the prostate via the rectum. However, the sensitivity of this traditional method is limited. It is 53 % in autopsy studies. This means that a prostate carcinoma is simply often overlooked during the biopsy (Fig. 1). If the detection of a prostate carcinoma is successful with the TRUS biopsy, the question arises as to whether the result of the biopsy actually correctly identifies the fine-tissue tumour stage. This is of immense importance for therapy planning or prognosis assessment of the disease.

In fact, the risk of misclassification, i.e. aggressive tumours are overlooked or underestimated in their aggressiveness, by conventional prostate biopsy is between 21 % and 54 % (Fig. 2 and 3). Ideally, the aggressive tumour requiring treatment should be biopsied and classified in a targeted manner (Fig. 4). This is the only way to ensure optimal and comprehensive counselling of the patient.

What is an mpMRI of the prostate?

The mpMRI of the prostate (= multiparametric magnetic resonance imaging of the prostate) is a modern imaging procedure in the diagnosis of prostate carcinoma.

This special magnetic resonance examination combines a standard examination with a contrast medium examination and a density measurement of the tissue.

This allows an experienced radiologist to find regions within the prostate that are most likely to be cancerous. Often these are tumours that are not reached by conventional punch biopsy. The mpMRI can distinguish clinically irrelevant tumours from aggressive tumours and thus help to avoid unnecessary interventions.

We cooperate closely here with the radiology department https://radiologie.merianiselin.ch/ of our premium partner, the Merian Iselin Klinik in Basel. A core team of 3 specialists is responsible here for the examination and reporting of mpMRIs of the prostate. With more than 500 examinations per year, we as referring physicians, but also our patients, can rely on a great deal of experience and a very high level of expertise in this field.

What is a robot-assisted mpMRI/TRUS fusion and mapping biopsy?

The images of the mpMRI examination are reviewed by the radiologist and the treating urologist together. Areas suspected of having a tumour are marked. On the day of the biopsy, these marked images are read into the biopsy device used to check the removal of tissue from the prostate (prostate biopsy). At alta uro, the mpMRI/TRUS fusion and mapping biopsy of the prostate is performed in a standardised robot-assisted manner using the Mona Lisa system (biobot).

The biopsies are taken via the perineum and not via the rectum. This virtually eliminates the risk of bacterial infection. The procedure is performed as a short inpatient procedure under anaesthesia.

Fusion biopsy

No focal therapy without robot-assisted mpMRI/TRUS fusion and mapping biopsy

Robot-assisted, perineal mpMRI/TRUS fusion and mapping biopsy of the prostate is a prerequisite for planning focal therapy. Transrectal biopsy of the prostate is insufficient for this purpose (see study 1 below).

Studies show a clearly precise prostate cancer diagnosis

In the PRECISION study (2) published in the renowned New England Journal of Medicine, it was shown for the first time with the highest scientific quality that the combination of MRI of the prostate and subsequent targeted fusion biopsy provides more precise results than conventional ultrasound-guided biopsy. Almost 30 % of the study participants who had received an MRI had unremarkable findings. Consequently, these patients were spared a prostate biopsy, which the other participants in the study (without MRI of the prostate) had to undergo.

Based on the MRI data and the targeted biopsy in the areas previously identified as abnormal, 38% were diagnosed with relevant prostate cancer. With the standard biopsy, relevant prostate cancer was found in only 26 % of the patients. These results show that the risk assessment of a suspected prostate cancer by MRI and fusion biopsy is significantly more precise than the ultrasound-guided biopsy practised so far.

In addition, this procedure reduces the diagnosis of a prostate carcinoma that usually does not require treatment by 50 %. Although these forms of prostate cancer do not pose a danger to the men affected, the diagnosis of "prostate cancer" often causes great psychological stress.

Studies cited

"When treating prostate cancer, the quality of life of those affected is our top priority. Focal therapy ideally complements our available treatment options and closes the gap between active surveillance and surgery or radiation."

Georg Müller, MD
alta uro, AG Basel