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Introduction: Stereotactic body radiation therapy (SBRT), the precise delivery of fewer high-dose fractions, may be radiobiologically favorable to conventional low-dose fractionation for prostate cancer radiotherapy. We report our early experience using definitive SBRT for treatment of localized prostate cancer.
Methods: Patients treated with SBRT at Georgetown University Hospital for localized prostate carcinoma, with or without the use of androgen deprivation therapy (ADT), were included in this retrospective analysis. Treatment was delivered using CyberKnife^® SBRT with doses of 35 Gy or 36.25 Gy in 5 fractions. Biochemical control was defined as a rise > 2 ng/ml above nadir (Phoenix definition) and analyzed using the Kaplan Meier method.
Results: Five hundred and sixty five patients (236 low-, 290 intermediate- and 39 high-risk) at a median age of 73 years (range, 48-96) received SBRT. A short-course of ADT was given to 17%. The median follow-up was 30 months. Median pre-treatment PSA was 6.2 ng/ml. The 5-year biochemical relapse free survival (bRFS) rate was 97.6%, 89.6% and 72.7% for low-, intermediate- and high-risk patients, respectively (p<0.001).
Conclusions: SBRT for clinically localized prostate cancer is a convenient treatment option with an early biochemical response similar to other radiation therapy treatments. The current evidence supports SBRT as a standard therapeutic option.