Novel application of stereotactic ablative radiotherapy using CyberKnife® for early-stage renal cell carcinoma in patients with pre-existing chronic kidney disease: Initial clinical experiences

The treatment of renal cell carcinoma (RCC) in patients diagnosed with chronic kidney disease (CKD) requires particular care in order to preserve the remaining renal function. The present study aimed to investigate the potential of a novel nephron-sparing treatment, which is capable of targeting tumors embedded deep within tissues. The present study analyzed three patients, with pre-existing CKD and multiple comorbidities, who were successfully treated for stage I RCC using the CyberKnife® stereotactic ablative radiotherapy (SABR) system. The total prescribed dose was 40 Gy in five fractions administered over five consecutive days. Treatment efficiency was determined using computed tomography scans of the tumors and periodic measurements of the glomerular filtration rate over a period of 12-40 months. Local control, defined as a radiologically stable condition, was achieved in all patients. Lung metastasis was observed in one patient nine months after SABR; however, the side-effects were generally mild and self-limiting. One patient developed renal failure 26 months after SABR, while the severity of CKD was only marginally altered in the other two patients and renal failure did not occur. In conclusion, in the present study, SABR with CyberKnife® was observed to be well tolerated in the patients, with an acceptable acute toxicity effect. Therefore, it may represent a potential therapeutic option for patients with early-stage RCC who have previously been diagnosed with CKD, but for whom other nephron-sparing treatments are contraindicated.