• Carcinologic efficacy at the site of treatment, [ Time Frame: at 5 years ]
  

• Overall carcinologic efficacy [ Time Frame: at 5 years ]
  
• Carcinologic efficacy and lack of adverse consequences on renal function [ Time Frame: at 5 years ]
  
• Local technical success
  

Background. Surgical treatment of multiple or recurrent renal tumors may be complicated by renal function impairment. Mini-invasive thermotherapy as radiofrequency (RF), induces necrosis of tumoral tissue while sparing normal renal parenchyma.

Objectives. The main objective is to assess the 5-year local carcinologic efficacy (no residual tumor tissue and no recurrence at the site of treatment) of the radiofrequency treatment. Secondary objectives are to assess 5-year overall carcinologic efficacy, predictive factors of technical success of RF procedures, and the general and renal tolerance 5 years after treatment.

Study design. Open label, randomized, parallel-group, multicentric clinical trial (9 centers).

Eligibility criteria. Patients with renal tumor in whom a surgical treatment may result in renal function impairment.

Intervention.

Experimental group: radiofrequency treatment, percutaneous or under laparoscopy, using RF 3000™ generator (Radiotherapeutics, Boston scientific) under a standardized heating protocol. A second procedure is allowed in case of residual tumoral tissue or tumor recurrence.

Control group: conservative kidney surgery.

Outcomes. The principal outcome is the 5-year local carcinologic efficacy (no residual tumor tissue and no recurrence at the site of treatment, as assessed by tomodensitometry or MRI after injection). Secondary outcomes are 5-year overall carcinologic efficacy (local efficacy and no metastases), renal function, technical success of RF procedures (no residual tumor tissue 2 months after procedure) and tolerance.

Follow-up. Clinical, biological and imaging follow-ups are scheduled 2 months, 6 months, 1, 2, 3, 4 and 5 years after the first treatment.