BERKELEY, CA (UroToday.com) - To ensure improved tumor control without increasing toxicity, several technical advances have been introduced for radiotherapy of localized prostate cancer. Intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT) are increasingly adopted to allow accurate targeting with the best possible protection of normal tissues. The application of a spacer to increase the distance between the prostate and the anterior rectal wall is a promising, innovative technique with only limited clinical data available.
The aim of this study was to prospectively analyze treatment-related toxicity for patients before and after IMRT, with a hydrogel spacer (78Gy), using a validated quality-of-life questionnaire. Patients had been surveyed before, at the last day, and 2-3 months after radiotherapy, using a validated questionnaire (Expanded Prostate Cancer Index Composite). Only patients who responded to the questionnaires at all three intervals were included in this analysis.
To differentiate between radiation-related symptoms and potential spacer-related symptoms, changes were compared to a subgroup of patients treated with the same technique and a similar dose (76Gy) and a second subgroup treated with a conventional three-dimensional conformal radiotherapy (3DCRT) technique (70.2Gy) (n=3 x 28 patients).
The SpaceOAR™ System (Augmenix Inc.) is a polyethylene glycol gel that polymerizes in seconds. An 18-gauge needle is advanced, via the transperineal approach, under transrectal ultrasound guidance. Following confirmation of proper needle location, the liquid hydrogel precursors are injected where they expand the perirectal space and then polymerize. The hydrogel maintains space for approximately three months during the complete duration of radiotherapy. It is absorbed in about six months.
Baseline mean bowel bother scores were 96 points in all subgroups. Prescription dose to the prostate was significantly higher for patients with a spacer in comparison to both other subgroups (p < 0.01). The mean prostate volume was 10cm3 and 9cm3 larger for patients with a spacer in comparison to patients in the 3DCRT and IMRT (without spacer) groups, respectively.
The hydrogel was injected without any complications. This study has shown that organ function recovered soon after the end of radiotherapy, so that problems were not reported within 2-3 months post therapy. A larger portion of the hydrogel is absorbed at this time (4-5 months after injection). The percentage of patients reporting moderate or significant bother with specific symptoms was not found to be greater for any category. Mean bother scores did not worsen by > 5 points for any category (urgency, frequency, diarrhoea, incontinence, bloody stools, pain). A non-significant mean bowel bother score decrease of 2 points
Written by:
Michael Pinkawa, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Department of Radiation Oncology, RWTH Aachen University, Pauwelsstr. 30, 52072, Aachen, Germany
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