Prognostic impact of biologically equivalent dose in stereotactic body radiotherapy for renal cancer.

Purpose /Objectives Materials/Methods: The National Cancer Database (NCDB) was queried (2004-2017) for patients with RCC who did not have surgical resection but received definitive SBRT. Kaplan-Meier analysis with log-rank test was used to evaluate overall survival (OS). Univariable (UVA) and multivariable (MVA) analysis were conducted using cox proportional hazard models to determine prognostic factors for OS. Results: A total of 344 patients with median age 77 (IQR 70-85) were included in this study. Median BED3 was 180 Gy (IQR 126.03-233.97). Median OS was 90 months in the highest quartile compared to 36-52 months in the lower three quartiles (p < 0.01). On UVA, the highest BED3 quartile was a positive prognostic factor (HR 0.67, p < 0.01 CI 0.51-0.91) while age, tumor size, T-stage, metastasis, renal pelvis location, and transitional cell histology were negative factors. On MVA, the highest BED3 quartile was remained significant (HR 0.69, p = 0.02; CI 0.49-0.95) as a positive factor, while age, metastasis were negative factors. Conclusion: Higher BED may be associated with improved OS. Prospective investigation is needed to clearly define optimal BED for SBRT used to treat RCC.