Diagnostics: Prostate biopsies

At GenesisCare, we provide specialist outpatient oncology, and are pioneering the use of transperineal prostate biopsies using local anaesthetic, a convenient alternative to general anaesthetic without the need for a hospital stay. At our centre in Cambridge, we also offer an innovative technique called transperineal Vector prostate biopsy which offers the benefits of a local anaesthetic procedure with improved patient tolerance and early results show a promising reduction in complications.

Over the past 30 years, transrectal ultrasound-guided (TRUS) biopsy of the prostate has been the model technique for diagnosing prostate cancers. During the procedure, an ultrasound probe is placed into the patient’s rectum and the image is used to guide a core needle into the prostate through the rectal wall. One of the most concerning constraints of this technique is that many aggressive cancers can go undetected during the procedure, particularly those in the anterior part of the prostate. Furthermore, there is a considerable risk of severe infectious complications to the patient.

In parallel with the rising awareness of the limitations of TRUS-guided biopsy, the use of multiparametric (mp) MRI–guided targeted biopsy has increased. MRI-guided prostate biopsy detects more clinically significant Gleason score 7–10 cancers and fewer insignificant Gleason score 6 cancers than TRUS biopsy. Additionally, MRI outperforms conventional TRUS biopsy in biopsy-naive patients. If MRI were to be used as part of a triage test, it could identify 25% of men who might safely avoid unnecessary biopsy, without impairing the detection of clinically significant cancer.

What is a transperineal biopsy?

Transperineal (TP) biopsy is a new diagnostic alternative to the more commonly used transrectal route. During this procedure, core biopsy needles are passed into the prostate through the perineum below the pubic arch.  It can be performed under general anaesthesia, or more recently, local anaesthesia.

There are several advantages of TP biopsy over TRUS biopsy, including:

• Better access to the anterior part of the prostate gland
• Fewer infectious complications – sepsis rates of less than 0.5%1
• Possibility of improving the three-dimensional location and documentation of the sampling by using a biopsy template with co-ordinates

Evidence-base of transperineal biopsy

In a multi-centre prospective outcome study between 2012 and 2016, 807 biopsy-naive patients underwent MRI-guided TP prostate biopsy, as the first diagnostic intervention.2 The aim of the study was to analyse patient outcomes of MRI-guided TP prostate biopsy, in cases where there was a suspicion of prostate cancer in three different tertiary referral centres, either by MRI/US-fusion or cognitive targeting.

236 patients had 18 to 24 systematic TP biopsies only, and 571 patients underwent additional targeted biopsies either by MRI-fusion or cognitive targeting if PI-RADS (prostate imaging-reporting and data system) ≥3 lesions were present. Prostate cancer was detected in 68% of the patients and Gleason score 7 to 10 cancer in 49%.

In 418 patients with PI-RADS 4–5 lesions using targeted plus systematic biopsies, the detection rate of prostate cancer with a Gleason score of 7 to 10 was significantly higher at 71% vs 59% and 61% with either approach alone (P < 0.001). For 153 PI-RADS 3 lesions, the detection rate was 31% with no significant difference to systematic biopsies with 27% (P >0.05).

MRI-based TP biopsy performed at high-volume tertiary care centres with a significant experience of prostate mpMRI and image-guided targeted biopsies yielded high detection rates of Gleason score 7 to 10 cancer. As such, prostate biopsies may not be needed for men with low PSAD and an unsuspicious MRI.

Transperineal prostate biopsy procedure under general anaesthesia

Prior to the biopsy, T1- and T2-weighted MRI scans are performed. If necessary, patients stop anti-coagulation drugs three to seven days before biopsy. Additionally, bowel preparation medication (glycerine suppositories) and oral ciprofloxacin are to be administered up to two hours before the procedure, and one dose of gentamycin a short period before the biopsy.3

• The T2-weighted MRI images with the lesions outlined are loaded into the system
• Surgeon draws the prostate’s contours on these images to obtain a three-dimensional representation of the gland
• The ultrasound probe inserted into the rectum – ultrasound images of the prostate are aligned with the MR image set using the fusion software
• Biopsies are performed – this may be done using a templated or targeted approach

Transperineal targeted prostate biopsy under local anaesthetic

Many centres worldwide, including the UrologyHubs at GenesisCare, are offering TP targeted prostate biopsy under local anaesthesic. Targeted biopsies may have similar detection rates for clinically significant disease as a template approach.4

This is a convenient approach offering seamless integration into a normal clinic workflow, patient convenience and avoidance of the risks or patient exclusions associated with general anaesthetic. The procedure has excellent cancer detection rates, with a prospective study showing 96% of men scoring 4 or 5 on mpMRI having Gleason pattern 4 disease.5 This study also reported minimal side effects and good tolerability.

Transperineal Vector prostate biopsy

TP Vector prostate biopsy is a novel and innovative technique for prostate cancer assessment. We are the first healthcare provider in the UK to offer this procedure which is available at our centre in Cambridge at our UrologyHub clinic.

The quality of well-established MRI US fusion transperineal template prostate biopsies under general anaesthesia is based on the high accuracy of the software, a fixed stepper mounted probe permitting minimal distortion of the prostate and visual tracking of needle by the template grid in-line with the US plain.

More recently introduced local anaesthetic TP biopsies use minimal numbers of entry points but require a mobile probe to allow inline needle tracking, which leads to distortion of the prostate, making visual or fusion targeting more difficult, as well as causing more discomfort for the patient.

VTRAX electromagnetic needle tracking, which provides needle trajectory tracking without direct view, allows the delivery of the benefits of the classic fusion TP biopsy technology, yet, through only two locally anaesthetised entry points whilst the probe and fusion can remain stable.

Evidence base of transperineal Vector prostate biopsy

We have evaluated TP Vector prostate biopsy since its introduction using patient reported outcome measures (PROMS) and oncological outcomes.

The procedure is extremely well tolerated. So far, no episode of retention has been reported and only one patient requested antibiotics for a minor urine infection.

Detection rates of targets are 95% with the highest ISUP grading or core length in the targets.

The new vector biopsies appear to deliver the high accuracy of established transperineal fusion technology with indication of improvement in tolerability and side-effects.

Transperineal Vector prostate biopsy procedure

Patients with an indication for TP biopsy based on PSA, rectal examination and MRI are offered vector prostate biopsy.

• Stepper-mounted ultrasound probe is placed in the rectum and local anaesthetic injected into the perineum
• The US image set is fused with the MRI
• A needle sheath with a VTRAX sensor is inserted into the perineum
• The trajectory of the needle is tracked in an electromagnetic field – a circle shows when the needle trajectory cuts the sagittal US plane, which can then be directed onto the lesion of interest for biopsy
• Targeted and systematic biopsies are taken

References 

1. Grummet J, Weerakoon M, Huang S, Lawrentschuk N, Frydenberg M, Moon D et al. Sepsis and ‘superbugs’: should we favour the transperineal over the transrectal approach for prostate biopsy?. BJU Int. 2014;114(3):384-8.
2. Hansen N, Barrett T, Kesch C, Pepdjonovic L, Bonekamp D, O’Sullivan R et al. Multicentre evaluation of magnetic resonance imaging supported transperineal prostate biopsy in biopsy-naïve men with suspicion of prostate cancer. BJU Int. 2017;122(1):40-49.
3. Hansen N, Patruno G, Wadhwa K, Gaziev G, Miano R, Barrett T et al. Magnetic Resonance and Ultrasound Image Fusion Supported Transperineal Prostate Biopsy Using the Ginsburg Protocol: Technique, Learning Points, and Biopsy Results. Eur. Urol. 2016;70(2):332-340.
4. Kasivisvanathan V, Dufour R, Moore C, Ahmed H, Abd-Alazeez M, Charman S et al. Transperineal Magnetic Resonance Image Targeted Prostate Biopsy Versus Transperineal Template Prostate Biopsy in the Detection of Clinically Significant Prostate Cancer. J Urol. 2013;189(3):860-866.
5. Bass E, Donaldson I, Freeman A, Jameson C, Punwani S, Moore C et al. Magnetic resonance imaging targeted transperineal prostate biopsy: a local anaesthetic approach. Prostate Cancer Prostatic Dis. 2017;20(3):311-317.