Stereotactic Body Radiation Therapy for Intermediate-risk Organ-confined Prostate Cancer: Interim Toxicity and Quality of Life Outcomes From a Multi-institutional Study

observed in 16% of the patients at a median of 36 months (range 6-60 months). The median bounce magnitude was 0.505 ng/mL (range 0.2-5.29 ng/mL). For the 335 cases with a minimum of 4 years of follow-up (median 53 months), the 5-year bRFS rates for low-risk and intermediaterisk cases were 97% and 89%, respectively. Conclusions: With a large cohort of patients treated with stereotactic body radiation therapy, with a reasonably long follow-up period, excellent efficacy was demonstrated at 5 years. For high-risk cases, the results are preliminary, given the small number of cases treated. However, for low and intermediate risk cases, these results compare favorably with other modalities. These results support a low alpha beta ratio for prostate cancer. Author Disclosure: A. Katz: F. Honoraria; Accuray. D. Freeman: F. Honoraria; Accuray. J. Aronovitz: None. D. Fuller: None. G. Bolzicco: None. R. Meier: None. S. Collins: G. Consultant; Accuray. J. Wang: None. M. Steinberg: None. C. King: None.