Primary site stereotactic ablative body radiotherapy in localized, recurrent, and metastatic renal cell carcinoma

Stereotactic ablative body radiotherapy (SABR) is an effective treatment for localized renal cell carcinoma (RCC). However, the role of primary site SABR for locally recurrent or metastatic RCC is unclear. Here, we report outcomes of primary SABR across a diverse cohort of localized, recurrent, and metastatic RCC patients treated at our institution.

RCC patients treated with SABR to lesions of the kidney or nephrectomy bed at our institution with at least 6 months of follow-up were included for analysis. Local control, overall survival, and freedom from distant failure were estimated using the Kaplan-Meier method. Estimated glomerular filtration rate (eGFR) was assessed at baseline and following SABR.

Fifty-three patients received primary site SABR. Thirty-seven (70 %) patients had localized RCC, and 16 (30 %) had metastatic RCC. Seven (13 %) had locally recurrent RCC after prior surgery or ablation. The median tumor size was 4.5 cm (IQR 3.7-6.3). At a median follow-up of 23 months (IQR 12-35), 2-year local control was 100 %, and 3-year local control was 94.4 % (95 % CI 84.4 %-100 %). Among patients with initially localized disease, the 2-year freedom from distant failure was 94.6 % (95 % CI 87.6 %-100 %), and the 2-year overall survival was 66.5 % (95 % CI 51.9 %-85.2 %). Twelve (23 %) patients experienced acute grade 1-2 treatment-related toxicity (nausea, vomiting, or small bowel). There were no acute grade 3-4 toxicities. Two (3.8 %) patients developed late grade 3 gastrointestinal toxicity. The median baseline eGFR was 51 mL/min/1.73 m² (IQR 38-77). At 1-year post-SABR, the median eGFR decline was 5 mL/min/1.73 m² (IQR -3 to 9). One patient required dialysis following SABR.

This analysis demonstrates excellent local control rates across patients with localized, recurrent, and metastatic RCC treated with SABR. Treatment was associated with minimal eGFR decline.