A novel method for decreasing rectal toxicity during prostate radiotherapy by prostate-rectum separation: An evaluation of irradiation dose parameters and acute side effects.

227 Background: Prostate cancers (PCA) frequently arise in the peripheral posterior zone of the gland and therefore adjacent to the rectum. Treatment can include brachytherapy and/or radiotherapy (RT); however, rectal toxicity can complicate therapy. A dilemma therefore arises in the balance between radiation dose and rectal adverse effects. Methods: Starting February 2012, until now 37 patients were included in this investigation. Under ultrasound guidance, a synthetic hydrogel (SpaceOAR) was injected between the prostate and the rectum, thus moving the rectum away from the high radiation dose volume, allowing dose escalation. The procedure was carried out in general anaesthesia and required approx. 10 min. The prescribed dose for the prostate was 80.0 Gy in 40 fractions. In 20 patients also the pelvic lymph nodes were irradiated with 50.4 Gy. IMRT planning was realized with and without hydrogel. During the treatment and 3 months after treatment acute toxicity was documented by the use of common toxicity...