Stereotactic Body Radiotherapy for Multiple Renal Cell Carcinoma Lesions in a Patient With Polycystic Kidney Disease After Partial Nephrectomy.

Renal cell carcinoma (RCC) is the most common malignant tumor of the kidney. Stereotactic body radiotherapy (SBRT) has recently emerged as a promising non-invasive treatment option for patients with localized RCC. However, data on SBRT in cases involving multiple renal lesions and pre-existing chronic kidney disease remain limited. We report a case of a 69-year-old male with a history of polycystic kidney disease and prior partial nephrectomy for RCC, who was found to have four new renal lesions during follow-up. At diagnosis of relapse, the patient was treated with SBRT using Cybernife®. All four lesions were treated simultaneously, with a total dose of 30 Gy in five consecutive fractions. No acute toxicity was observed. At the last follow-up, 29 months after SBRT, the MRI confirmed the stable disease observed at the previous controls. Renal function remained stable throughout the follow-up period. This case supports the use of SBRT as a safe and effective alternative to surgery for patients with multiple RCC lesions and compromised renal function. Even with a reduced dose, SBRT achieved long-term disease control and preservation of renal function suggesting its suitability in selected complex cases.