Stereotactic ablative radiotherapy (SAbR) is a promising alternative for selected renal cell carcinoma (RCC) patients with oligometastasis. The objective of this study was to evaluate the potential of SAbR as a tactical approach for longitudinal control in persistently oligometastatic RCC patients. We report on the impact of SAbR on tumor control rates as well as its tolerability in systemic therapy naïve patients with oligometastatic disease (without brain metastases) and to assess the effect of SAbR on subsequent first line systemic therapy by comparison to historical controls.
We reviewed patients with metastatic RCC treated with frontline SAbR with a curative intent from 2007 to 2017 at UT Southwestern Kidney Cancer Program. We analyzed local control rates (LCR), toxicity, freedom from systemic therapy (FST), type and duration of first line systemic therapy, and overall survival (OS). Cox regression and Kaplan-Meier analyses were used.
We identified 47 patients with oligometastatic RCC treated with SAbR to 65 lesions, 21 patients had more than one metastatic site treated. LCR was 91.5% at 2 years with no reported grade ≥3 toxicity. With a median follow-up of 30 months (IQR:13.7-40.9), median FST from first SAbR was 15.2 months (95%CI:8.8-40.1). The most common systemic therapies initiated after SAbR were pazopanib (60.7%) and sunitinib (14.3%). Improved FST was observed in patients with metachronous disease (HR=2.67, p=0.02), those presenting with solitary metastasis (HR=2.26, p=0.05) and non-bone metastasis (HR 2.21, p=0.04). 1-year and 2-year OS after SAbR were 93.1% (95%CI:80.1-97.7) and 84.8% (95%CI:69.1-92.9), respectively. Median OS was not reached.
SAbR is an effective and safe treatment for selected patients with oligometastatic RCC, can provide longitudinal disease control without systemic therapy for over a year, and does not appear to adversely impact the effectiveness of first line systemic therapy once initiated. Prospective validation of these findings is being sought through a phase II trial at UT Southwestern.
International journal of radiation oncology, biology, physics. 2019 Jul 29 [Epub ahead of print]
Yuanyuan Zhang, Jonathan Schoenhals, Alana Christie, Osama Mohamad, Chiachien Wang, Isaac Bowman, Nirmish Singla, Hans Hammers, Kevin Courtney, Aditya Bagrodia, Vitaly Margulis, Neil Desai, Aurelie Garant, Hak Choy, James Brugarolas, Robert Timmerman, Raquibul Hannan
Department of Radiation Oncology., Kidney Cancer Program, Simmons Comprehensive Cancer Center., Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas., Department of Internal Medicine, Hematology-Oncology Division; Kidney Cancer Program, Simmons Comprehensive Cancer Center., Kidney Cancer Program, Simmons Comprehensive Cancer Center; Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas., Department of Internal Medicine, Hematology-Oncology Division; Kidney Cancer Program, Simmons Comprehensive Cancer Center. Electronic address: ., Department of Radiation Oncology,; Kidney Cancer Program, Simmons Comprehensive Cancer Center. Electronic address: .