Key Clinical Summary: 

•  Stereotactic ablative radiotherapy provided durable local control (93%) with minimal toxicity in patients with oligoprogressive metastatic renal cell carcinoma, enabling deferral of systemic therapy escalation.
• Patients with fewer progressive lesions (< 2) derived the greatest benefit, while increasing lesion number was associated with significantly shorter modified progression-free survival.
• A non-significant signal toward improved outcomes was observed when stereotactic ablative radiotherapy was delivered concurrently with immunotherapy, supporting further prospective investigation.

Lucian Zhao, MD, UT Southwestern Medical Center, discusses outcomes from a large retrospective analysis evaluating stereotactic ablative radiotherapy in patients with oligoprogressive metastatic renal cell carcinoma undergoing systemic therapy. 

Results demonstrated that stereotactic ablative radiotherapy achieved high local control while delaying the need for systemic therapy escalation, with outcomes strongly influenced by the number of progressive lesions at treatment. These findings help refine patient selection and support stereotactic ablative radiotherapy as a patient-centered strategy in oligoprogressive metastatic renal cell carcinoma. 

These results were presented at the 2026 ACRO Radiation Oncology Summit in Orlando, Florida. 

Transcript:

Essentially, oligoprogression is a subset of patients with metastatic cancer who develop progression on a limited number of sites while on systemic therapy and typically, it represents tumor resistant clones and Darwinian selection pressure. Stereotactic radiation (SABR) can provide good local control, and our hypothesis is that we can use SABR in conjunction with continuing and effective systemic therapy to provide good local control and then not having to switch to the next line of systemic therapy without compromising patients' overall survival. 

We did a retrospective review at UT Southwestern with the GU radiation oncology and medical oncologists, as well as some of urologists from 2010 to 2023, and we looked at patients who had more than 1 site of treatment but less than 5 at the time of SBRT and had at least 2 months of prior systemic therapy. Exclusion criteria were switching systemic therapy without evidence of disease progression or not having sufficient follow up by 3 months. Our primary end point was a modified progression-free survival (mPFS) and that's the next time new systemic therapy or death. Our cost progression was done on mPFS as well as overall survival. 

We found that after we treated 96 patients who had 150 lesions the next line systemic therapy or death was about 9 months. Patients who had only 1 site treated had significantly longer time to next line or death, that was 13 months versus only 7 months in patients who had more than 1 lesion. We also found that having 1 prior line of systemic therapy had worse overall survival. Lastly, we found that patients who are on immunotherapy versus a tyrosine kinase inhibitor had a trend towards improved mPFS, but not statistically significant. 

SBRT or SABR has durable control benefits, particularly [in patients with] only 1 lesion. There's a trend towards improvement when going on [immunotherapy], but that wasn't statistically significant and that will be further investigated in respective trials. We found a pretty good cohort of patients who had less disease burden, particularly just having 1 lesion, and that reflects probably just underlying more indolent oncology.

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