A dosimetric study of polyethylene glycol hydrogel in 200 prostate cancer patients treated with high-dose rate brachytherapy ± intensity modulated radiation therapy

Background and purpose: We sought to analyze the effect of polyethylene glycol (PEG) hydrogel on rectal doses in prostate cancer patients undergoing radiotherapy. Materials and methods: Between July 2009 and April 2013, we treated 200 clinically localized prostate cancer patients with high-dose rate (HDR) brachytherapy +/- intensity modulated radiation therapy. Half of the patients received a transrectal ultrasound (TRUS)-guided transperineal injection of 10 mL PEG hydrogel (DuraSeal((TM)) Spinal Sealant System; Covidien, Mansfield, MA) in their anterior perirectal fat immediately prior to the first HDR brachytherapy treatment and 5 mL PEG hydrogel prior to the second HDR brachytherapy treatment. Prostate-rectal, and bladder doses and prostate-rectal distances were calculated based upon treatment planning CT scans. Results: There was a success rate of 100% (100/100) with PEG hydrogel implantation. PEG hydrogel significantly increased the prostate-rectal separation (mean +/- SD, 12 +/- 4 mm with gel vs. 4 +/- 2 mm without gel, p < 0.001) and significantly decreased the mean rectal D-2 (mL) (47 +/- 9% with gel vs. 60 +/- 8% without gel, p < 0.001). Gel decreased rectal doses regardless of body mass index (BMI). Conclusions: PEG hydrogel temporarily displaced the rectum away from the prostate by an average of 12 mm and led to a significant reduction in rectal radiation doses, regardless of BMI. (C) 2014 Elsevier Ireland Ltd. All rights reserved.