Multi-centre Randomized Clinical Trial: 106 patients with confirmed unilateral high-volume low risk (Gleason score 3 + 3) or intermediate risk prostate cancer (Gleason score 3 + 4) will undergo an IRE treatment. These patients will be randomized into one of the two groups of the study.

Group 1: Focal ablation of the prostate at the side of the positive biopsies (focal-ablation) Group 2: Extended ablation of the prostate (extended ablation)

Patients will have an ultrasound of the prostate and the imaging data will be entered into the Planning Software system of the IRE-device. The volume of the prostate is measured and a specified ablation zone will be determined. The patients will be admitted for overnight stay in the hospital on the morning of the scheduled IRE procedure. The IRE will be performed under general anaesthetic and the specified zone identified in the planning stage will be ablated. Two to four IRE electrode needles will be placed into the prostate under ultrasound image guidance with a perineal approach using a brachytherapy grid. When the needles are in place, electric pulses of one to two minutes duration are used to ablate the specified zone. The total procedure time will be approximately 1 hour.

Safety data will be collected and patients will be followed up at 1 day post-operatively, 1 month, 3 months, 6 months and 1, 2 and 3 year(s) post IRE.

Inclusion Criteria

1. Histologically confirmed organ-confined unilateral prostate cancer with adjacent positive biopsies on transperineal template prostate biopsies or MRI targeted biopsies in combination with systematic biopsies (clinical stage T1c-T2b)
2. Gleason sum score 6 or 7
3. PSA <15 ng/ml or PSA > 15 ng/mL counselled with caution
4. Life expectancy of > 10 years

Exclusion Criteria

1. Bleeding disorder as determined by prothrombin time (PT) > 14.5 seconds, partial thromboplastin time (PTT) > 34 seconds, and Platelet Count < 140/uL
2. No ability to stop anticoagulant or anti-platelet therapy for 7 days prior the procedure.
3. Active urinary tract infection (UTI)
4. History of bladder neck contracture
5. Anaesthesia Surgical Assignment category IV or greater
6. History of inflammatory bowel disease
7. Concurrent major debilitating illness
8. Prior or concurrent malignancy except for basal cell carcinoma of the skin
9. Cardiac history including arrhythmias, ICD or pacemaker
10. Prostate calcifications greater than 5 mm.
11. Biologic or chemotherapy for prostate cancer
12. Hormonal therapy for prostate cancer within 6 months prior to procedure
13. Previous radiation to pelvis
14. Transurethral resection of the prostate / Urethral stent
15. Prior major rectal surgery (except haemorrhoids)