NanoKnife (Irreversible Electroporation)

The simple idea

NanoKnife is the brand name of a system used to deliver Irreversible Electroporation. The medical team places several thin needles into and around a small target area inside the body. The machine then sends short, strong electrical pulses between the needles.

The pulses make tiny permanent holes in the cell walls of the cells inside the planned target zone. Those cells then die. Cells just outside the target zone are not affected in the same way.

How it is different from heat or cold treatments

Most other "focal" cancer treatments work by heating tissue (radiofrequency, microwave or HIFU) or freezing it (cryotherapy).

NanoKnife is different - it uses electrical fields, not temperature. The supporting framework of nearby blood vessels, ducts and nerves is largely preserved. In urology this matters because:

• The nerves on either side of the prostate control erections.
• The urethra and the muscle that controls urination sit very close to the prostate.

Treatments that work by heating or freezing can damage these structures more than IRE does. That is the main reason IRE is being considered as a focal option for selected localised prostate cancer.

What is it being used for at Urology NSW?

The main use in Dr Kooner's practice is focal therapy for selected localised prostate cancer - treating only the part of the prostate where significant cancer has been clearly seen on MRI and confirmed by biopsy, rather than treating the whole gland.

NanoKnife sits alongside the other prostate cancer pathways the practice offers:

• Active surveillance for very low-risk cancers.
• Robotic radical prostatectomy (whole-gland removal).
• Single port robotic surgery (one small cut).
• Radiotherapy and brachytherapy.
• Other focal and experimental treatments (HIFU, cryotherapy).

IRE has also been studied overseas for selected small kidney tumours, primary liver cancer and locally advanced pancreatic cancer, but these uses are research-level and need a dedicated multidisciplinary team. The detailed page covers this in more depth.

What the evidence shows so far

The evidence base is newer and smaller than for surgery or radiotherapy, but it has grown rapidly. The main published findings for focal IRE in localised prostate cancer are:

• Encouraging short- to medium-term cancer control in carefully selected men. An Australian series (Stricker group, Sydney) reported 5-year outcomes in 123 men: most remained free from progression to whole-gland or systemic treatment.
• Low rates of significant urinary incontinence in published series. Most men return to baseline continence within the first weeks.
• Better preservation of erections than is typically reported for radical prostatectomy or radiotherapy, though still not zero risk.
• UK NICE guidance (2023) supports the use of IRE for prostate cancer with standard arrangements for consent, governance and audit.
• European Association of Urology guidelines (2024) list focal therapies including IRE as options that should be offered within a clinical trial or a well-defined registry, because long-term head-to-head data against surgery or radiotherapy do not yet exist.

What is not yet available is long-term cancer outcome data (10 years and beyond) at the same depth as exists for surgery or radiotherapy. The longest published primary focal IRE prostate series report follow-up at around 5 years.

Who is it for - and who is it not for?

Focal IRE may be considered for men who have:

• A clearly localised prostate cancer with a single dominant area visible on multiparametric MRI, confirmed on a targeted biopsy.
• Cancer of low-to-intermediate grade in a position that allows the treatment zone to safely cover the lesion.
• A priority on preserving urinary and sexual function, accepting that ongoing PSA and MRI surveillance is essential.

It is usually not the right choice for men with:

• High-grade or large-volume prostate cancer.
• Cancer in both halves of the gland or evidence the cancer has grown beyond the prostate.
• Cancer too close to the urethra or the muscle that controls urine, where a safe margin is not possible.
• A preference for the treatment with the longest published track record - in which case surgery or radiotherapy remain the established options.

What to expect

• Anaesthetic. Done under a general anaesthetic with full muscle relaxation. The anaesthetic team also monitors your heart rhythm so the pulses are delivered between heart beats.
• Time in theatre. The pulse part is short. Most single-zone focal IRE prostate procedures take around an hour to an hour and a half of theatre time, plus time for the anaesthetic and the imaging set-up.
• Hospital stay. Same day or one overnight stay, depending on the hospital and individual factors.
• Catheter. A urinary catheter is left in for a short period (usually a few days to about one week) to let the prostate settle. It is removed at a clinic visit.
• Pain. The perineum (the area between the scrotum and the back passage) is bruised or tender for a few days. Most men manage on simple oral pain relief.
• Wounds. No skin cuts to heal - only the small needle puncture sites in the perineum.
• Return to activity. Walking from the day of the procedure, desk work usually after about a week, no heavy lifting or strenuous exercise for two to three weeks.
• Follow-up. Structured PSA testing and a follow-up MRI (commonly at around 6 to 12 months), with a repeat targeted biopsy of the treated area where it is needed.