Hydrogel Spacer Prospective Multicenter Randomized Controlled Pivotal Trial: Dosimetric and Clinical Effects of Perirectal Spacer Application in Men Undergoing Prostate Image Guided Intensity Modulated Radiation Therapy

Neil Mariados, John Sylvester, Dhiren Shah, Lawrence Karsh, Richard Hudes, David Beyer, Steven Kurtzman, Jeffrey Bogart, R. Alex Hsi, Michael Kos, Rodney Ellis, Mark Logsdon, Shawn Zimberg, Kevin Forsythe, Hong Zhang, Edward Soffen, Patrick Francke, Constantine Mantz, Peter Rossi, Theodore DeweeseDaniel A. Hamstra, Walter Bosch, Hiram Gay, Jeff Michalski

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120 Scopus citations

Abstract

Purpose Perirectal spacing, whereby biomaterials are placed between the prostate and rectum, shows promise in reducing rectal dose during prostate cancer radiation therapy. A prospective multicenter randomized controlled pivotal trial was performed to assess outcomes following absorbable spacer (SpaceOAR system) implantation. Methods and Materials Overall, 222 patients with clinical stage T1 or T2 prostate cancer underwent computed tomography (CT) and magnetic resonance imaging (MRI) scans for treatment planning, followed with fiducial marker placement, and were randomized to receive spacer injection or no injection (control). Patients received postprocedure CT and MRI planning scans and underwent image guided intensity modulated radiation therapy (79.2 Gy in 1.8-Gy fractions). Spacer safety and impact on rectal irradiation, toxicity, and quality of life were assessed throughout 15 months. Results Spacer application was rated as "easy" or "very easy" 98.7% of the time, with a 99% hydrogel placement success rate. Perirectal spaces were 12.6 ± 3.9 mm and 1.6 ± 2.0 mm in the spacer and control groups, respectively. There were no device-related adverse events, rectal perforations, serious bleeding, or infections within either group. Pre-to postspacer plans had a significant reduction in mean rectal V70 (12.4% to 3.3%, P<.0001). Overall acute rectal adverse event rates were similar between groups, with fewer spacer patients experiencing rectal pain (P=.02). A significant reduction in late (3-15 months) rectal toxicity severity in the spacer group was observed (P=.04), with a 2.0% and 7.0% late rectal toxicity incidence in the spacer and control groups, respectively. There was no late rectal toxicity greater than grade 1 in the spacer group. At 15 months 11.6% and 21.4% of spacer and control patients, respectively, experienced 10-point declines in bowel quality of life. MRI scans at 12 months verified spacer absorption. Conclusions Spacer application was well tolerated. Increased perirectal space reduced rectal irradiation, reduced rectal toxicity severity, and decreased rates of patients experiencing declines in bowel quality of life. The spacer appears to be an effective tool, potentially enabling advanced prostate RT protocols.

Original languageEnglish (US)
Pages (from-to)971-977
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume92
Issue number5
DOIs
StatePublished - Aug 1 2015

All Science Journal Classification (ASJC) codes

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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    Mariados, N., Sylvester, J., Shah, D., Karsh, L., Hudes, R., Beyer, D., Kurtzman, S., Bogart, J., Hsi, R. A., Kos, M., Ellis, R., Logsdon, M., Zimberg, S., Forsythe, K., Zhang, H., Soffen, E., Francke, P., Mantz, C., Rossi, P., ... Michalski, J. (2015). Hydrogel Spacer Prospective Multicenter Randomized Controlled Pivotal Trial: Dosimetric and Clinical Effects of Perirectal Spacer Application in Men Undergoing Prostate Image Guided Intensity Modulated Radiation Therapy. International Journal of Radiation Oncology Biology Physics, 92(5), 971-977. https://doi.org/10.1016/j.ijrobp.2015.04.030