Neoadjuvant SAbR shows promising outcomes in RCC with tumor thrombus

Data presented at 2025 Society of Urology Oncology Annual Meeting in Phoenix, Arizona showed promising oncological efficacy demonstrated the safety and feasibility of neoadjuvant SAbR followed by surgery in patients with newly diagnosed renal cell carcinoma (RCC) and caval tumor thrombus. Overall, the regimen showed promising oncological efficacy with limited toxicity in this high-risk RCC population.

In an interview with Urology Times®, presenting author Lin Lin, MD, discussed the background and key findings from the study. Lin is a urologic oncology fellow at UT Southwestern Medical Center in Dallas, Texas.

"The goal of this study was to see if radiating the tumor thrombus before surgery would allow it to help prevent tumor thrombi [embolization] somewhere else and cause recurrences," Lin explained.

In total, the prospective phase 2 study included 23 patients with newly diagnosed RCC. Patients received neoadjuvant SAbR as 40 Gy over 5 fractions or 36 Gy over 3 fractions, followed by surgery. The median follow-up was 35.2 months.

Data showed a 12-month relapse-free survival (RFS) of 71.4% (80% CI, 56.6 to 82.0; P = .087). This compared favorably with the historical surgery-alone cohort, which had a 12-month RFS of 55.7%. Overall survival and cancer-specific survival at 12 months were both 95.2%.

Neoadjuvant SAbR was also found to be safe and feasible, with no radiation-related adverse events (AEs) of grade 4 or higher nor any reported cases of pulmonary embolism. Perioperative AEs of grade 3 or higher were reported in 36.4% of patients.

REFERENCE

1. Lin L. Late Breaking Abstract: Phase II trial of neoadjuvant stereotatic ablative radiotherapy for caval tumor thrombus in newly diagnosed renal cell carcinoma. Presented at: Society of Urologic Oncology Annual Meeting; December 2-5, 2025; Phoenix, Arizona