e16006 Background: We evaluated the initial acute toxicities experienced by patients treated with cyberknife fractionated radiosurgery for low and low-intermediate risk prostate cancer. Methods: Twenty-two patients with low or low-intermediate risk prostate cancer (T2a, GG 3+3=6 or 3+4=7, PSA <10) were enrolled prospectively on an IRB approved protocol and treated the planning target volume (PTV)(prostate+5mm margin) with cyberknife fractionated radiosurgery to a dose of 36.25 Gy in 5 fractions (7.25Gy/fraction). The target volume included the prostate and seminal vesicles. PSA values, AUA symptom scores (AUA SS), and NCI CTC acute toxicities were analyzed prior to radiosurgery and at 1 month (N=16), 3 months (N=12) and 6 months (N=5)post-treatment. Results: Patients treated on study included 12 with GG 3+3=6 cancer and 10 with GG 3+4=7 cancer. Mean patient age was 66 years old (range 49–79). Mean pre-treatment PSA was 5.29 (range 0.64–9.36) declining to 3.44 (range 0.00–10.43) at 1 month post treatment, 1.99 (range 0.31–3.99) at 3 months post-treatment and 2.08 (1.05–3.13) at 6 months post-treatment. Mean pre-treatment AUA SS was 7 (range 0.–18) increasing to 12 (range 2–29) at 1 month post treatment, decreasing to 8 (range 2–17) at 3 months post-treatment and 11 (3–17). There were 5 grade 1 acute toxicities including (diarrhea, fatigue, mild urinary frequency, hemorrhoid and a rash) and 7 grade 2 toxicities including (bladder spasms, painful urinary, bowel irregularity, rectal pain, urethritis and numbness in the upper thigh), all grade 1 and 2 toxicities resolved within three months of treatment. The one patient with grade 2 thigh numbness was not thought to be study related toxicity. Two patients developed grade 3 toxicity. One developed bacteremia after the transrectal ultrasound guided placement of the fiducials, the infection completely resolved after treatment with antibiotics. One patient on Coumadin developed hematuria which resolved with conservative management. Conclusions: Cyberknife fractionated radiosurgery for patients with early stage prostate cancer appears to be safe on our early initial assessment.Continued evaluation and longer follow-up ongoing. [Table: see text]
Hypofractionated passively scattered proton radiotherapy for low- and intermediate-risk prostate cancer is not associated with post-treatment testosterone suppression