Irreversible Electroporation for Prostate Cancer (IRE or Nanoknife™)

The prostate is an organ that lies just below the bladder. In younger men it is about the size of a walnut but its size tends to increase as you get older. It surrounds the beginning of the urethra, the tube that transports urine from the bladder to the tip of the penis. During ejaculation it secretes a fluid that forms part of the semen. Cancer can develop within the prostate. It is called localised if it has not spread to other areas of the body. 

The main function of the prostate is to supply fluid for the sperm during ejaculation. Prostate Specific Antigen (PSA) is produced by the prostate gland and measuring its level in the bloodstream is one of the tests used to look for prostate cancer. 

Prostate cancer begins when the cells in the prostate start to divide and grow out of their normal pattern. They do not grow into normal prostate tissue but instead grow into lumpy bundles of cells called tumours. Tumours disrupt the normal function of the prostate, and cells that come free from the tumour can travel elsewhere in the body, and begin to grow tumours there. Prostate cancer may be:  

• localised (only affecting the prostate) 
• or it may be locally advanced (spread outside the outer capsule of the prostate but not into the blood stream)  
• or metastatic (the cancer has moved outside the prostate and into the bloodstream and may affect other organs).  

Your surgeon will be able to discuss what type of tumour you have and the likelihood of this spreading. The treatment recommended will depend on the size and site of your tumour.

IRE treats prostate cancer focally but without the need for heating or freezing the tissue. Instead, pulses of electricity create tiny holes in cancer cells, causing them to die. The low energy direct current (LEDC) can be very finely pinpointed, making this method highly accurate and lending to its commercial name: NanoKnife. The NanoKnife treatment takes approximately 1-2 hours.   

During IRE, special needles or probes are passed into the prostate through the perineum in a similar manner to the prostate biopsy you had. Your doctor will use ultrasound images of the prostate to confirm that the needles are in the correct position. IRE is a new procedure at UCLH but our team has experience of its use in other hospitals. IRE belongs to a group of prostate cancer treatments called focal therapies, These all depend on the same ultrasound technique to identify the area of the prostate needing treatment and we have been providing them for large numbers of patients for over 15 years.

You may be suitable for prostate IRE treatment if you have localised prostate cancer – that is, the cancer has been shown to be within the prostate only. At UCLH we use IRE as a focal treatment, directing it at only one part of the prostate. The remainder of the prostate is left untreated, one of the reasons that the side effects of focal treatment are less. This means the remainder of the prostate should either not contain any cancer or contain only low risk cancer that can be safely watched and may well never need treating.  

Three main tests are used to find out which treatments men are suited to: 

1. Scans such as MRI and PET scans are used to identify where the cancer is in your prostate and to check if the cancer is confined to the prostate.  
2. The prostate biopsy takes tissue samples from the prostate to find out whether cancer is present and which parts of the prostate it is present in. At UCLH the biopsy is targeted at areas of the prostate that appear suspicious on the MRI scan. 
3. The PSA blood test, which for most men will have been carried out at the GP and triggered their MRI and biopsy in the first place, can also give us information about how much cancer is present and which scans or treatments might be useful.  

Most men who are diagnosed with prostate cancer will have options for treatment. Your team will explain what your options are, and you’ll have a chance to talk to the teams that offer each different treatment that we think will treat the cancer.

There is no overall best treatment for localised prostate cancer. Each treatment has side effects and advantages and disadvantages. Treatments will affect all men differently and you may not get all of the side effects. It’s important to think about how you would cope with these before choosing a treatment.

The benefits of IRE for localised prostate cancer include: 

• It’s a minimally invasive (no incisions) procedure.  
• It preserves sensitive structure (i.e. nerves) around the treatment zone, this contributes to a low rate of side-effects. 
• A short hospital stay- in the vast majority of cases men go home on the same day as treatment. 
• A rapid recovery once you’re home, which means that you can return to normal life quickly. 
• Men who are treated with IRE (or any of the focal treatments) are followed up carefully using the PSA blood test, MRI scans and sometimes prostate biopsy.  
• If more, suitable prostate cancer is detected in follow up IRE may be repeated, or a different prostate cancer treatment chosen. 
• As IRE is a newer treatment for prostate cancer we do not yet have the data to tell us how effective it is at controlling cancer in the long term. The largest study at present, published in 2019, showed 5% of men needed a different prostate cancer treatment (such as surgery to remove the prostate or radiotherapy) three years later and 10% of those treated underwent a second IRE treatment during those three years.  
• Men who need another cancer treatment after IRE may be suitable for radiotherapy, keyhole surgery to remove the prostate (prostatectomy) or drug treatment. 
• IRE is being offered at UCLH as a normal NHS treatment, not as part of a clinical trial. Nonetheless we will be analysing and in due course publishing the (anonymized) results of IRE prostate cancer treatment to increase understanding of this newer prostate cancer amongst doctors and patients and in line with NICE guidance on IRE.

All treatments and procedures have risks and we will talk to you about the risks of IRE for localised prostate cancer.   

Problems that may happen straight away 

• A small number of men have difficulty in passing urine after the treatment and therefore patients have a tube (catheter) inserted at the time of the procedure to help with this. This is often left in for a week or so to allow swelling to settle. 
• Some men will notice swelling of their penis or scrotum, which may happen in the first or second week after the procedure. This is temporary and will usually resolve within a few months. 
• Blood in the urine, semen and from the back passage can occur but will settle down after a few days. The blood in the semen can sometimes last weeks or even a few months but shouldn’t cause any harm. 
• A few men (3 or 4 in a hundred) may get an infection in the urinary system following treatment with IRE. This will usually settle with some antibiotic tablets. 

Problems that may happen later  

• Erectile dysfunction (problems getting or maintaining an erection) is possible as the nerves involved in creating an erection lie just behind the prostate gland and could be affected during the IRE procedure. This occurs in around 10% of patients and tends to recover over a year.  
• Retrograde ejaculation (a dry orgasm) can develop in about 20% of patients due to the scar in the treated area especially if more extensive treatments are used. 
• Urine incontinence (leakage of urine) can occur after treatment, but this is very rarely permanent. Some men do wear pads to protect their underwear for a few days following the procedure. If this occurrence persists, we can teach pelvic floor exercises that will help your urinary control. In large series 99% of men were continent a year after IRE (pad free).   
• Fistula – This is an abnormal connection between the prostate and the rectum (back passage). It can happen very rarely after most of the prostate cancer treatments but can require bowel surgery and a stoma (bowel bag on the tummy) to put right. It is extremely rare after IRE, affecting 1 man in 500 or less.

This depends on the risk category of your disease and whether you then opt for a different treatment. High risk categories of prostate cancer usually require some form of treatment. In this case, if you do not have treatment (whether IRE or any other form of treatment) then the risk to you in terms of the cancer progressing is high. Delay in this instance may mean that treatment cannot be given later and it could also mean that there is a risk to your life without any treatment. 

Studies have shown that men who are in a low risk group (and some medium risk men) can be safely managed by active surveillance for many months to years and if they show signs of progression, they can have treatment at that point. Many men who choose treatment do not like the thought of having no treatment for cancer, so they choose a form of treatment that they want. Your doctor will have told you what risk category you are in. If you are unsure, please ask your doctor or specialist nurse to explain.

You will be given an appointment for an assessment with a pre-assessment nurse several weeks before your operation. As part of this you will be given instructions about what you should bring with you on the day of the operation, whether you should continue taking all your medications as normal, what time you should arrive on the day and for how long you should fast before your arrival. On the actual day of the operation, you will be given an enema one to two hours prior to the procedure. This involves putting liquid in your back passage to empty it, which allows us to obtain a clear ultrasound picture during the IRE treatment. The IRE treatment takes between one to two hours under general anaesthetic (this means you will be asleep) and you will be able to go home the same day providing that there is someone to accompany you. Occasionally we may ask you to stay overnight if you do not have an escort to take you home or if you have medical problems that mean remaining in hospital is safest.

We want to involve you in all the decisions about your care and treatment. If you decide to go ahead with prostate IRE, by law we must ask you to sign a consent form before proceeding with the treatment. This confirms that you agree to have the procedure and understand what it involves. Your surgeon will explain all the risks, benefits and alternatives before they ask you to sign a consent form. If you are unsure about any aspect of your proposed treatment, please don’t hesitate to speak with a senior member of staff again.

During IRE, special needles or probes are passed through the skin in front of the anus (back passage) and behind the scrotum (this area is called the perineum) and placed into the prostate. Typically three to four probes are placed with a maximum of six. The surgeon uses ultrasound images of the prostate to confirm that the needles are in the correct position. Depending on the distance between the needles, voltages of up to 3000V will be applied in very short pulses (90 microseconds). These pulses will create small holes in the cellular membrane of the cells within the targeted area, causing the cells to die. The dead cells will be removed from the area by the body’s own cleaning system called the macrophages.  Once the desired set of pulses is given between each needle pair, the needles will be removed and you will be brought to the recovery unit.  

Before the procedure starts, a catheter will be placed in the penis for urine drainage. Rarely this is not possible, and a suprapubic catheter placed through a 1cm below the belly button is used instead. A telescope passed through the penis, called a cystoscope, is used to guide this. Insertion of a suprapubic catheter carries additional but very low risks of damaging the structures around the bladder This catheter will be left in place for a few days. On rare occasions, depending on the location of the tumour inside the prostate and the size, the catheter might be left in place for longer. Your doctor will inform you about this at the pre-surgical meetings.

Most people recover from the IRE treatment within one to two weeks. In the days after the operation, you will probably feel more tired than usual. This is normally because of the anaesthetic. You should drink plenty of fluid every day, around 1.5 to 2 litres. This will prevent you from becoming dehydrated and make urine infection less likely. Also, you should avoid constipation as this leads to straining. To help with this you will be given a gentle laxative syrup when you leave the hospital. As regards the IRE needle puncture sites in the skin in front of your anus (back passage), you should simply aim to keep this area clean and dry - no dressings should be needed in this area once you leave the hospital. 

• Pain - It is normal to expect some discomfort after your IRE treatment particularly in and around the area that the IRE needles were inserted. You will be provided with some pain killers on discharge from hospital and you can get more from your general practitioner if necessary.
• Bleeding – occasionally, there may be slight bleeding from the area in front of your anus (back passage) where the needles or probes used for IRE were inserted (this area is termed the perineum). If this occurs, you can apply a dry dressing.
• Bruising and swelling of scrotum – you may develop some bruising in the area that the IRE needles were inserted (perineum) or you may get some swelling of your scrotum after the procedure. Both will settle without any treatment over a couple of months.

• If possible bath or shower daily. Otherwise wash the skin around the catheter once a day. 
• Always wash your hands with soap and water before and after handling any part of the catheter.  
• If you have a urethral catheter, make sure you clean around the entry site of the catheter, and clean the catheter itself using downward strokes away from the catheter. This should be done morning and night and after emptying your bowels. 
• If you have a urethral catheter and you are uncircumcised, pay attention to washing under the foreskin. After washing be sure to replace the foreskin in its usual position. 
• When emptying your catheter, make sure that the end of the bag does not touch the toilet bowl or seat. 
• Always be sure to change your leg bag or catheter valve every seven days or sooner, if they become soiled. 
• If you use a night bag, simply connect directly to your leg bag or catheter valve, as this will help protect you from infection. 
• Before you go to sleep ensure the catheter tap or valve is open, the drainage tap on the night bag is closed, and that urine is draining. 
• Dispose of the catheter bags by emptying urine into toilet and putting the bag in household rubbish. 
• For the first 24 hours you should allow your catheter to drain freely into the catheter bag (leg bag). At night you may choose to attach it to a larger night bag. 
• After 24 to 48 hours disconnect the bag from the catheter and attach a catheter valve. Your ward nurse may have already attached this, in which case remove the catheter bag from the valve. 
• When the valve is switched off (i.e. in the up position) your bladder will fill with urine. Once you feel the need to pass urine open the tap, empty the urine down the toilet then close the tap again.

• Urine Infection – While you have a catheter in place it is usual to have a harmless increase in the number of bacteria in your urine, this does not need treatment. However, if you experience one or more of the following new symptoms you should contact your GP: New lower back pain, high temperature and feeling generally unwell, cloudy offensive urine, worsening bladder pain or spasm. 
• Blood in your urine – This is common after IRE treatment and may continue for up to two months after IRE treatment. It is not a cause for concern unless you have a high temperature or fever, or if the bleeding is persistent or heavy. If you are concerned please contact your GP or specialist nurse. 
• Debris or sediment in the urine – You may see some tissue, debris or sediment in your urine this is common after IRE treatment. You should aim to drink 1.5 to 2 litres daily. This will encourage catheter drainage and should prevent your catheter from blocking. 
• Urine leakage – This may occur from around the catheter site or the urethra (water pipe). If this occurs you should check that your catheter is not blocked or release your catheter valve to empty the bladder. If leakage is associated with a strong sensation of urgency, you may be experiencing bladder spasms. 
• Blockage of catheter – This can be partial or total. If you think your catheter is blocked you should check it is not kinked and try changing your position. If still no urine drains or you experience abdominal discomfort your catheter may need to be changed. You should seek immediate medical attention with your GP or local Accident and Emergency department. 
• Bladder spasms - Having a urinary catheter in place can sometimes give rise to "bladder spasms". This may be felt as a strong or urgent sensation of the need to pass urine before the bladder is full. This occurs because both the catheter, and the catheter balloon (which holds the catheter in place) irritates the bladder. Occasionally you may experience leakage of urine when you have a bladder spasm. This is because the spasm can cause a strong contraction of the bladder muscle which in turn can force urine out in an uncontrolled manner. The urine leakage may be around the catheter or catheter entry site, or via the urethra.  
• Sometimes the spasm may give rise to a sensation of discomfort or pain in the tip of the penis particularly after urinating. (This sensation can also occur at the end of emptying the bladder via the catheter valve.) Not all men will experience bladder spasms and severity of these can vary. It is important to remember that this will settle once the catheter is removed but in the meantime, you may find it helpful to try not to force urine out when you have a spasm but rather try to relax and focus on deep breathing until the spasm passes. If the bladder spasms are frequent and very troublesome then contact your GP practice or specialist nurse for further advice as there are medications to help with this. It may also be helpful to check that you do not have a urine infection if the spasms are very severe. 
• You may experience discomfort or stinging when you start to pass urine normally. This will subside. Make sure you continue to drink 1.5 to 2 litres of fluid per day. 

Your bladder emptying will be assessed once the catheter has been removed in clinic (trial without catheter clinic or ‘TWOC’). For this appointment expect to be in the department for around 3-4 hours. This will allow time for the catheter to be removed and for an assessment to be made that you are able to empty the bladder. 

• If you wish to have the catheter removed locally please contact your nurse specialist at University College Hospital at Westmoreland Street or your GP who can liaise with your local services to arrange this. Ideally this should be arranged well in advance of your IRE treatment as not all district or practice nurses are happy to manage the catheter removal. Some hospital departments may also decline. If you are not having the catheter removed locally you will automatically be given a TWOC clinic appointment at UCLH. You will be discharged home – with your escort. 
• A contact number will be given if you have any problems at home.

After IRE treatment, it is important that you are monitored by your GP and hospital. Although many men can expect a cure from this treatment, some men may need further treatments. 

You will need regular check-ups and PSA (prostate specific antigen) blood tests after prostate cancer treatment. Usually the PSA will be first tested three months AFTER your IRE procedure when we will also see you in the outpatient clinic, then at three monthly intervals with your GP for the first year. We will ask your GP to take over the PSA monitoring and to update us with the readings should it rise above a level that we have advised you and your GP. After this time if the PSA is stable, we will advise the frequency of PSA monitoring be reduced to six monthly intervals for a period of two years, then to annual intervals.   

We would anticipate a reduction in the PSA value after IRE. The amount the PSA value may fall by varies from man to man and depends on how much of the prostate is left behind. An MRI scan is done after one year and repeated later in follow up. We may also offer you an MRI one week after your treatment. 

You will also be monitored for any urine or erection problems and offered support or treatment, as necessary. If you experience any difficulties with your erections or urine symptoms, please speak to your doctor or contact your nurse specialist 

You should note that on discharge from the hospital, you will be given an appointment to see your surgical team three months following your prostate IRE. We will usually organise an MRI scan of the prostate in one year depending on what the PSA results show.

We hope this information page is helpful. If you have any questions, please ask your doctor or nurse.

Prostate Cancer UK      

Tel: 0800 074 8383    

UCLH Macmillan Support and Information Service  

Location: Ground Floor, Huntley Street, London, WC1E 6DH 

Tel: 020 3447 8663   

Email: supportandinformation@uclh.nhs.uk 

Macmillan Cancer Support      

Tel: 0808 808 00 00     

UCL Hospitals cannot accept responsibility for information provided by external organisations.

Clinical Nurse Specialists 

Karen Wilkinson, Nora Chu, Beth Penhaligon, Lilian Hamuntili, John Lunas and Jonathan Soriano 

07984 391 126  

uclh.prostatecancercns@nhs.net 

Pathway Coordinator to Professor Emberton, Professor Caroline Moore, Mr Arya, Mr Orczyk and Mr Grey (Consultants in Urology) 

Tel: 020 3447 9194 

Fax: 020 3447 9303 

Out of hours, please contact your GP or nearest Accident & Emergency Department.