5-fraction SBRT improves outcomes in osseous renal cell carcinoma metastases

Local-control outcomes are encouraging in patients with osseous renal cell carcinoma metastases who went through five fractions of stereotactic body radiotherapy (SBRT), reports a study.

“The best fractionation for SBRT in renal cell carcinoma metastases has not been well defined,” the investigators said. “In addition, the literature on outcomes using 5-fraction SBRT in the setting of osseous metastases has not been well reported.”

To address this, the team conducted this study on 39 patients (median age at diagnosis 58.4 years) with 69 osseous renal cell carcinoma metastases who were treated using 5-fraction SBRT at a single institution using two dose-fractionation schemes. Kaplan-Meier curves were used to assess overall survival and local-control outcomes of the two fractionation methods.

Sixty-nine lesions were included in the study, of which 20 were treated with 30 grays (Gy) in five fractions and 49 with 40 Gy in five fractions.

At 1 year, the local-control rate for all treated lesions was 85.5 percent (59/69), with a local-control of 90 percent (18/20) for lesions receiving 30 Gy and 83.7 percent (41/49) in lesions receiving 40 Gy. No statistically significant difference was observed in 1-year local-control rate between the two fractionation schemes (p=0.553).

“Patients with osseous renal cell carcinoma metastases undergoing 5 fractions of SBRT had favourable LC outcomes,” the investigators said. “There was no difference in survival or LC between the 40 Gy and 30 Gy treatment arms.”