The purpose of this study is to determine if trans-rectal microwave ablation of the index tumor of patients with low-risk prostate cancer is sufficiently precise and safe, using MRI-transrectal ultrasound image registration.

In men with low-risk prostate cancer, European and American guidelines recommend either active surveillance or whole-gland treatments, with significant induced morbidity and burden on quality of life. Focal treatments of the index tumor are currently under investigation to decrease morbidity while proposing active treatment.

The purpose of this study is to determine the feasibility, precision and safety of a novel ablation treatment using microwaves, delivered transrectally under real-time guidance with MRI-transrectal ultrasound image registration. The index tumor will be detected with prostate MRI and characterized with targeted biopsies using MRI-transrectal ultrasound image registration. It will then be ablated with microwaves using the same transrectal approach and guidance system (KOELIS).

Inclusion Criteria:

• Patients aged from 45 to 76 years old ;

• Life expectancy above 10 years ;

• Diagnosis of prostate cancer confirmed on prostate biopsies ;

• Low risk of progression, defined with D'Amico criteria :

  • T1c or T2a stage
  • Maximum Gleason score of 3+4, including targeted biopsies corresponding to less than 50% grade 4 for the tumor
  • Prostate Specific Antigen <15 ng/mL

• Detection of the index tumor with prostate MRI, characterized with targeted biopsies using MRI-transrectal ultrasound image registration ;

• Patient accepting to be followed after the procedure using active surveillance protocol standards ;

• Patient affiliated to national health care insurance ;

• Free consent, informed and written, dated and signed by the patient and the investigator before enrollment.

Exclusion Criteria:

• Medical past history of prostatic surgery ;
• Medical past history of radiotherapy or pelvic trauma ;
• Medical past history of acute or chronic prostatitis
• severe BPH-related urinary tract symptoms defined as an IPSS >18 ;
• Extra-capsular extension or seminal vesicle invasion on prostate MRI.
• Tumor involvement > 3 mm on systematic biopsies outside the tumor volume detected on MRI.
• Tumor largest axis > 20 mm on prostate MRI ;
• Distance of less than 5 mm between the tumor and the rectum
• Patient unable to understand the course of the study
• History of allergy or non-tolerance to gadolinium salts used in MRI
• Patient with a contraindication to performing an MRI
• Person placed under safeguard of justice