Stereotactic ablative body radiotherapy (SABR) is increasingly utilized for treating primary renal cell carcinoma (RCC), yet its impact on renal function remains uncertain. This retrospective single-institution analysis aimed to assess the incidence and predictive clinical factors associated with severe to end-stage chronic kidney disease (CKD) following SABR for RCC. From 2012 to 2020, adult patients with localized RCC, no metastatic disease, baseline estimated glomerular filtration rate (eGFR) of ≥ 30 ml/min/1.73 m², and at least one post-SABR eGFR at six months or later were analyzed. Patients with upper tract urothelial carcinoma were excluded. The primary outcome was freedom from severe to end-stage CKD, determined using the Kaplan–Meier estimator. 

Cox proportional hazard models assessed the impact of baseline CKD, age, hypertension, diabetes, tumor size, and fractionation schedule. Seventy-eight consecutive patients (median age: 77.8 years; tumor size: 4.5 cm) with a median follow-up of 42.2 months were included. The baseline median eGFR was 58 ml/min, with 55% of patients having baseline CKD stage 3. By the last follow-up, 2.8% of baseline CKD 1–2, 25.9% CKD 3a, and 68.8% CKD 3b patients had developed CKD stage 4–5. The estimated probability of freedom from CKD stage 4–5 at 1 and 5 years was 89.6% and 65%, respectively. Univariable analysis revealed worse baseline CKD (p < 0.0001) and multi-fraction SABR (p = 0.005) as predictive of stage 4–5 CKD, with only the former remaining significant in the multivariable model. 

In conclusion, SABR demonstrated satisfactory nephron sparing and acceptable rates of severe to end-stage CKD in this elderly cohort with pre-existing renal dysfunction, making it a viable option for medically inoperable patients.

Source: ro-journal.biomedcentral.com/articles/10.1186/s13014-024-02413-w