Clinical results of shaped beam radiosurgery and X-ray assisted patient positioning for prostate cancer

Abstract

4702 Background: Cure rates of localized prostate cancer after radical prostatectomy, brachytherapy or external beam radiotherapy are comparable. Therefore the choice between these treatments largely depends upon their potential toxicity. We analyzed side effects and biochemical control of patients with localized prostate cancer treated with shaped beam radiosurgery (SBRS). The Novalis Body (BrainLAB AG., Heimstetten, Germany) system was used for patient positioning. Methods: Between May 2000 and October 2002, 100 patients (90% stage T1-T2) were treated. Median follow-up is 12m (range 3–29m). Depending upon the risk group the patient belonged to, the isocenter dose was either 70 Gy or 78 Gy in 2 Gy/fraction. Positioning prior to each treatment was performed using Novalis Body. The system is based on automated image fusion between digitally reconstructed radiographs from the planning CT and orthogonal X-ray images and was shown to be superior to conventional positioning. Treatment was done by SBRS using the m3 mMLC micromultileaf collimator. Toxicity was scored using RTOG criteria and biochemical failure was defined according to the ASTRO consensus panel definition. Results: Acute grade 0/1/2 gastro-intestinal (GI) toxicity was seen in 88/12/0 patients. Acute grade 0/1/2 genito-urinary toxicity was seen in 46/39/15 patients. No late GI side effects have occurred thus far. One patient experienced late radiation cystitis with hematuria, which was controlled by coagulation. Two-year biochemical control after SBRS was 96%. Conclusions: Prostate cancer patients treated by SBRS therapy and using X-ray assisted positioning show a low rate of early side effects. Further follow-up is needed to confirm the low rate of late side effects and the favorable biochemical control. No significant financial relationships to disclose.