Trans-rectal Focal Microwave Ablation of the Index Tumor in Patients With Low-risk Prostate Cancer

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