Effect of a prostate-rectum hydrogel spacer on reducing acute radiation proctitis: A single center experience

Gastrointestinal (GI) and genitourinary (GU) toxicity was assessed during and after conventional IMRT in 21 low to intermediate risk cancer patients that had received an absorbable hydrogel spacer between the prostate and the rectum. The transperineal hydrogel injection resulted in the creation of 11.5 mm space between the prostate and rectum; space that was not decreased throughout radiotherapy. The resulting rectal dose reduction following hydrogel application was 60.3%, relative to the potential rectal dose without the spacer. Hydrogel application was tolerated well, with a 38% rate of acute Grade 1 GI toxicity, and with no Grade 2 acute or chronic GI toxicity reported. The rates of acute and chronic Grade 2 or greater GU toxicity were 24% and 0% respectively. Images taken six months following application suggested hydrogel absorption, supported by a decrease in the prostate-rectum space to within 3 mm of baseline. Proctoscopy performed 15 months after hydrogel application showed no signs of telangiectasia, ulceration, stricture or necrosis.