Prospective analysis of hydrogel spacer for patients with prostate cancer undergoing radiotherapy

Objective To report on the dosimetric benefits and late toxicity outcomes after injection of hydrogel spacer ( HS ) between the prostate and rectum for patients treated with prostate radiotherapy ( RT ). Patients and Methods In all, 76 patients with a clinical stage of T1–T3a prostate cancer underwent general anaesthesia for fiducial marker insertion plus injection of the HS into the perirectal space before intensity‐modulated RT ( IMRT ) or volumetric‐modulated arc RT ( VMAT ). HS safety, dosimetric benefits, and the immediate‐ to long‐term effects of gastrointestinal ( GI ) toxicity were assessed. Results There were no postoperative complications reported. The mean (range) prostate size was 66.0 (25.0–187.0) mm . Rectal dose volume parameters were observed and the volume of rectum receiving 70 Gy ( rV 70 ), 75 Gy ( rV 75 ) and 78 Gy ( rV 78 ) was 7.8%, 3.6% and 0.4%, respectively. In all, 21% of patients (16/76) developed acute Grade 1 GI toxicities, but all were resolved completely by 3 months after treatment; whilst, 3% of patients (2/76) developed late Grade 1 GI toxicities. No patients had acute or late Grade ≥2 GI toxicities. Conclusion Injection of HS resulted in a reduction of irradiated rectal dose volumes along with minimal GI toxicities, irrespective of prostate size.