Minimally Invasive Tumor Therapy (MITT)

Department of Radiology, Charité – Universitätsmedizin Berlin

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  7. Onik G, Rubinsky B (2010) Irreversible Electroporation: First Patient Experience Focal Therapy of Prostate Cancer. Series in Biomedical Engineering 2010, pp 235-247
  8. Valerio M, Stricker PD, Ahmed HU, et al. (2014) Initial assessment of safety and clinical feasibility of irreversible electroporation in the focal treatment of prostate cancer. Prostate Cancer Prostatic Dis. 2014 Sep 2. doi: 10.1038

Focal Treatment of Prostate Cancer with Irreversible Electroporation (IRE)


Prostate cancer is the most common cancer in men (1), constituting 20% of all male cancer cases. Ninety percent of cases are diagnosed in men over the age of 60. However, prostate cancer accounts for only 10% of cancer deaths in men. This means that most men diagnosed with prostate cancer will not die of the disease – a fact that is also underlined by the results of autopsy studies, which revealed prostate cancer in 85% of healthy men above the age of 85 (2 - 5).


When there is a well-founded suspicion of prostate cancer, a transrectal biopsy of the prostate should be obtained (6). This is done by a urologist, who will use ultrasound (US) for guidance to obtain 10 – 12 tissue specimens from different regions of the prostate for microscopic examination by a pathologist. If the tissue examination (histology) confirms the diagnosis of prostate cancer, the stage of the disease will be determined using the classification of the Union internationale contre le cancer (UICC criteria). This classification distinguishes between local cancer (cancer confined to the prostate gland without invasion of surrounding tissue and without metastatic spread to lymph nodes or other organs) and advanced prostate cancer (lymph node metastases or organ metastases, cancer growth beyond the prostate or infiltration of nearby organs).


Local prostate cancer is divided into 3 risk groups (low, intermediate, and high risk) using laboratory findings (prostate-specific antigen (PSA) level) and biopsy results (Gleason score, which indicates the aggressiveness of prostate cancer) as criteria.


These are the most important criteria in deciding on the best treatment for a patient. Men with low-risk local prostate cancer have a good prognosis and are not candidates for surgery (resection) or radiation therapy because, in these cases, the risks of treatment are greater than the risk of prostate cancer. For these low-risk cases, active surveillance is the strategy of choice. Active surveillance means that the prostate cancer is not treated. Instead, these patients are closely monitored by regular clinical examinations, laboratory tests, and imaging studies (ultrasound, magnetic resonance imaging).


Men with a low-risk prostate cancer for whom active surveillance is recommended but who wish to have their cancer treated are candidates for a new focal treatment method offered by our department.


Focal Treatment of Prostate Cancer


Over the last two decades, localized or focal treatment procedures have been developed and established for many solid tumors in various organs like the liver, kidneys, and lungs. Focal treatment is less radical because it targets only the cancerous part of the organ.


More recently, there has been an increasing interest in also establishing such focal treatment procedures for prostate cancer patients.


Focal treatment of prostate cancer is an intermediate option between active surveillance and radical therapies that involve treating the entire prostate gland (surgical removal or radiotherapy).


Advantages of Focal Treatment


Radical prostate cancer therapies bear the risk of serious complications because they can harm important anatomical structures around the prostate that are needed for sexual function (potency) and bladder control (urinary continence). This is why there is an increasing demand for less damaging, focal treatments, which will, in most cases, allow doctors to spare critical structures near the prostate (such as the nerves).


Irreversible electroporation (IRE) is a novel, minimally invasive therapy that has been shown to have advantages over other focal treatments. IRE is an ablation technique that destroys cancer cells by exposing them to strong local electrical fields. The electricity creates tiny holes (called pores) in cell membranes, causing cell death in the treated area. An important advantage of IRE over other minimally invasive ablation techniques (such as radiofrequency ablation (RFA), cryoablation, or high-intensity focused ultrasound (HIFU)) is that it causes little damage to noncellular tissue components. Blood and lymphatic vessels, the urethra and nerves are made up of cells within a complex and stable tissue matrix. With an intact matrix, as is the case after IRE, cells can regenerate after treatment. As a result, important structures in the treated area like the urethra and nerves are typically not harmed by IRE or, if so, only temporarily.


The high local electrical currents which are passed through the cancer cause substantial muscle contractions (jerks). Hence IRE is performed under general anesthesia.


IRE in Prostate Cancer


Given the advantages of IRE outlined above and promising first results in patients with small and localized prostate cancer (7, 8), we now also offer IRE in our clinic.


IRE is not an option for all patients with prostate cancer. There are several conditions (inclusion criteria) that must be met and also some reasons that preclude a patient from having IRE (exclusion criteria).


Inclusion criteria

  • Male patient aged over 18 with histologically confirmed cancer on one side of the prostate (unilateral) without spread to lymph nodes or distant organs (classified as T1-2aN0M0)
  • PSA ≤ 15 ng/ml (9); Gleason score ≤ 3+4 (10). The cancer inside the prostate must be visible on MR images, and clinically relevant cancer portions outside the planned treatment area must be ruled out
  • Life expectancy ≥ 10 years


Exclusion criteria

  • Advanced stage of prostate cancer
  • Metastases in other organs or lymph nodes
  • Patients who have undergone radiotherapy or focal treatment of the prostate (e.g., HIFU, RFA, cryotherapy)
  • Androgen suppression/hormone treatment within the last 12 months before planned IRE
  • Patients who have had major prostate surgery
  • Known allergy to MRI contrast agents or local anesthetics
  • Cardiac pacemakers or metal implants which are not safe in the MRI scanner
  • Multiple other illnesses, cardiac arrhythmia
  • Reduced kidney function (with a glomerular filtration rate (GFR) < 35ml/min)


How Does IRE Work?


Irreversible electroporation (IRE) is a novel approach that kills cancer cells by passing a strong electrical current through the tissue. The current destroys cancer cells by creating tiny openings (pores) in their membranes. In a process known as phagocytosis, specialized cells of the body’s immune system (macrophages) swallow and remove the dead cancer cells. IRE is performed under general anesthesia because the high electrical currents can cause muscle contractions. The pulsed electrical fields are generated with thin needles, which are inserted and advanced into the prostate cancer through the skin in the area between the anus and the scrotum (perineum) under image guidance. Image guidance allows the interventional radiologist to monitor the procedure during needle positioning. We use an advanced technique called MRI-US fusion for guidance during IRE. This technique combines MR images acquired before treatment with ultrasound images acquired during the procedure. MRI-US fusion images make the procedure very safe because they clearly show the tumor and allow precise needle positioning. Treatment starts once the needles have been positioned. The whole procedure takes about an hour.


Figure 1: Image-guided insertion of the IRE electrode through the perineum using a special template (grid) for positioning. The interventional radiologist uses image guidance throughout the procedure.




Patients scheduled for IRE will be hospitalized for 2 - 4 days. There are no restrictions on daily activities after the procedure. You should have a follow-up magnetic resonance imaging (MRI) examination of the prostate 6 – 8 weeks after IRE and then every 3 months. Follow-up MRI is performed to assess the outcome of treatment and to rule out recurring prostate cancer. You can have your follow-up MRI as an outpatient in our department or elsewhere. If the MRI is done at another site, we kindly ask you to send us a CD with the images for evaluation and quality control. In addition, the outcome of treatment should be monitored by PSA tests.


For further information on IRE of prostate cancer, please do not hesitate to contact us. We will be happy to answer any questions you may have.


  • Contact:

Minimally Invasive Tumor Therapy (MITT)

Charité, Campus Virchow-Klinikum

Department of Radiology

Augustenburger Platz 1

13353 Berlin, Germany

Phone: +49 (0)30/450-557309

Fax: +49 (0)30/450-557947 oder


Case Examples


Figure 2: This patient with prostate cancer (arrows) in the peripheral zone of the prostate on the right side was examined by multiparametric MRI – an imaging test of the prostate that combines different MR techniques to improve detection and evaluation of prostate cancer. (a) In a T2-weighted MR image, prostate cancer is revealed as a darker area in the otherwise brighter peripheral zone. (b and c) So-called diffusion-weighted images can reveal cancer by making visible the movement of water molecules. Molecule movement is uninhibited in normal tissue but decreased in cancer tissue due to an increased cellularity. (d) Prostate cancer is characterized by high blood flow (hypervascularization), which makes the cancer appear brighter on images obtained after administration of contrast medium.


Figure 3: Appearance of a prostate cancer in MRI (left, T2-weighted image) and in the corresponding ultrasound view (right). In both images, the cancer is encircled by a green line and appears darker.