Debra Freeman, MD – Naples Christopher King, MD, PhD - Stanford

Corresponding author Debra Freeman, MD CyberKnife Centers of Tampa Bay/Wellspring Oncology 5935 Webb Rd. Tampa, FL, USA

Background Stanford prostate CK program initiated 12/03 Naples prostate CK program initiated 2/05 Both programs focused on low-risk patients: T1c-T2a disease; PSA < 10.0; Gleason score < 7 Stanford data initially published in spring of 2009 (IJROBP); updated 2010 Naples data published in fall of 2009 (TCRT)

Current study Combined cohort of 41 pts. with low risk disease No prior hormonal therapy Median 5 yr. follow-up (range yrs) (T1c-T2a, GS <7, PSA <10)

Treatment Planning Homogeneous planning used for all pts. PTV = GTV (prostate) + 3-5mm Stanford: Gy in 5 fractions Naples: 35 Gy in 5 fx Dose covered at least 95% of PTV Consecutive treatment days

Kaplan-Meier biochemical disease-free survival curve after SBRT for prostate cancer. Median follow-up is 5-years. Three of the 41 patients recurred, at 33, 37 and 42 months post-treatment. Tick marks indicate censored patients.

Results 5 yr. biochemical progression-free survival = 93% Median PSA nadir = 0.3 Three pts with biopsy-confirmed local recurrence; metastatic work-up negative Remaining pts with stable or declining PSA levels

Toxicity No RTOG grade 3 rectal toxicity One RTOG grade 3 urinary toxicity (dysuria) No incontinence reported RTOG Grade IIIIIIIV Urinary 25% (10/41) 7% (3/41) 2.5% (1/41) 0% Rectal 13% (6/41) 2.5% (1/41) 0%

Treatment comparison Treatment option 5 yr. bDFS Prostatectomy IMRT LDR brachy HDR brachy SBRT* 76-92% 69-89% 83-88% 90-92% 93% *current study

Summary Five-year results of SBRT for localized prostate cancer demonstrate the efficacy and safety of shorter courses of high dose per fraction radiation delivered with SBRT technique. Ongoing clinical trials are underway to further explore this treatment approach.