This observational study is designed to expand the current database available in the literature and the existing knowledge on the outcomes and safety of radiofrequency ablation (RFA) for the treatment of primary renal cell carcinomas in stage T1a. All interventions and subsequent follow-ups are clinical decisions are independent of the study, given its observational nature.

Patient selection criteria will be those typically established by each participating center t with T1a primary renal tumors for which a Multidisciplinary Tumor Board has indicated as candidates for treatment with radiofrequency ablation.I

Inclusion Criteria:

• Age ≥18 years
• Signed informed consent approved by the Ethics Committee prior to the ablation procedure.
• RCC in stage T1a (size <4 cm), single or multiple, histologically demonstrated by percutaneous biopsy before or within 30 days prior to ablation
• Absence of comorbidities that contraindicate treatment
• Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0-2 at baseline screening.

Exclusion Criteria:

• No specific exclusion criteria are established for this clinical registry due to its observational nature. Each center will apply its own criteria according to its routine clinical practice.

Patients with primary renal cell carcinomas in stage T1a