Key Clinical Takeaways:

• Design/Population: This large retrospective analysis evaluated 96 patients with oligoprogressive metastatic renal cell carcinoma treated with stereotactic ablative radiotherapy to 153 lesions during ongoing systemic therapy between 2010 and 2023.
• Key Outcomes: Stereotactic ablative radiotherapy achieved high local control (93%) with minimal toxicity and a median modified progression-free survival of 9.2 months, with outcomes strongly influenced by the number of progressive lesions treated.
• Clinical Relevance: These findings support stereotactic ablative radiotherapy as a patient-centered strategy to delay systemic therapy escalation in carefully selected patients with oligoprogressive metastatic renal cell carcinoma and highlight the need for prospective studies to refine patient selection and explore potential synergy with immunotherapy.

According to findings from a large retrospective analysis, stereotactic ablative radiotherapy (SAbR) provides durable local control and delays systemic therapy escalation in selected patients with oligoprogressive metastatic renal cell carcinoma receiving systemic therapy.

These results were presented by Lucian Zhao, MD, UT Southwestern Medical Center, Dallas, Texas, at the 2026 ACRO Radiation Oncology Summit in Orlando, Florida. 

In this study, investigators evaluated data from 96 patients with oligoprogressive metastatic renal cell carcinoma who received SAbR to 153 progressive lesions between 2010 and 2023. The primary end point was modified progression-free survival (mPFS), defined as time from SAbR to systemic therapy switch or death, with systemic therapy escalation analyzed as a competing-risk event. Key secondary end points included overall survival (OS), local control, and safety. 

At a median follow-up of 59 months, median mPFS was 9.2 months, with a 1-year estimated mPFS of 38%. Patients with 2 to 3 progressive lesions (hazard ratio [HR], 2.10; 95% CI, 1.29 to 3.43; P = 0.003) and those with 4 to 5 lesions (HR, 2.84; 95% CI, 0.41 to 1.05; P = .08) experienced a significantly higher risk of systemic therapy escalation or death compared with patients with a single progressive lesion. Local control following SAbR was 93%, with only 1 reported grade 3 adverse event.

OS was inferior among patients who had received >1 prior line of systemic therapy before SAbR. A nonsignificant trend toward improved mPFS was observed among patients treated with immunotherapy at the time of SAbR.

“This approach provided high local control with minimal toxicity while deferring systemic therapy escalation, supporting its role as a resource-sparing, patient-centered strategy,” concluded Dr Zhao.

Source: 

Zhao L. Stereotactic ablative radiotherapy for oligoprogressive metastatic RCC: Predictors of prolonged systemic therapy benefit. Presented at the 2026 ACRO Radiation Oncology Summit. February 4 - 7, 2026. Orlando, Florida. Abstract 1612