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™ 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.