{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T23:17:08Z","timestamp":1779923828240,"version":"3.53.1"},"reference-count":39,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2023,1,6]],"date-time":"2023-01-06T00:00:00Z","timestamp":1672963200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Current Oncology"],"abstract":"<jats:p>Background: The aim of this study is to examine the dosimetric influence of endorectal balloons (ERB) on rectal sparing in prostate cancer patients with implanted hydrogel rectum spacers treated with dose-escalated or hypofractionated intensity-modulated proton beam therapy (IMPT). Methods: Ten patients with localized prostate cancer included in the ProRegPros study and treated at our center were investigated. All patients underwent placement of hydrogel rectum spacers before planning. Two planning CTs (with and without 120 cm3 fluid-filled ERB) were applied for each patient. Dose prescription was set according to the h strategy, with 72 Gray (Gy)\/2.4 Gy\/5\u00d7 weekly to prostate + 1 cm of the seminal vesicle, and 60 Gy\/2 Gy\/5\u00d7 weekly to prostate + 2 cm of the seminal vesicle. Planning with two laterally opposed IMPT beams was performed in both CTs. Rectal dosimetry values including dose-volume statistics and normal tissue complication probability (NTCP) were compared for both plans (non-ERB plans vs. ERB plans). Results: For ERB plans compared with non-ERB, the reductions were 8.51 \u00b1 5.25 Gy (RBE) (p = 0.000) and 15.76 \u00b1 11.11 Gy (p = 0.001) for the mean and the median rectal doses, respectively. No significant reductions in rectal volumes were found after high dose levels. The use of ERB resulted in significant reduction in rectal volume after receiving 50 Gy (RBE), 40 Gy (RBE), 30 Gy (RBE), 20 Gy (RBE), and 10 Gy (RBE) with p values of 0.034, 0.008, 0.003, 0.001, and 0.001, respectively. No differences between ERB and non-ERB plans for the anterior rectum were observed. ERB reduced posterior rectal volumes in patients who received 30 Gy (RBE), 20 Gy (RBE), or 10 Gy (RBE), with p values of 0.019, 0.003, and 0.001, respectively. According to the NTCP models, no significant reductions were observed in mean or median rectal toxicity (late rectal bleeding \u2265 2, necrosis or stenosis, and late rectal toxicity \u2265 3) when using the ERB. Conclusion: ERB reduced rectal volumes exposed to intermediate or low dose levels. However, no significant reduction in rectal volume was observed in patients receiving high or intermediate doses. There was no benefit and also no disadvantage associated with the use of ERB for late rectal toxicity, according to available NTCP models.<\/jats:p>","DOI":"10.3390\/curroncol30010058","type":"journal-article","created":{"date-parts":[[2023,1,6]],"date-time":"2023-01-06T03:31:28Z","timestamp":1672975888000},"page":"758-768","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Is an Endorectal Balloon Beneficial for Rectal Sparing after Spacer Implantation in Prostate Cancer Patients Treated with Hypofractionated Intensity-Modulated Proton Beam Therapy? A Dosimetric and Radiobiological Comparison Study"],"prefix":"10.3390","volume":"30","author":[{"given":"Dalia","family":"Ahmad Khalil","sequence":"first","affiliation":[{"name":"Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), 45147 Essen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8260-3523","authenticated-orcid":false,"given":"J\u00f6rg","family":"Wulff","sequence":"additional","affiliation":[{"name":"Faculty of Physics, TU Dortmund University, 44227 Dortmund, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Danny","family":"Jazmati","sequence":"additional","affiliation":[{"name":"Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), 45147 Essen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dirk","family":"Geismar","sequence":"additional","affiliation":[{"name":"Faculty of Physics, TU Dortmund University, 44227 Dortmund, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0512-1146","authenticated-orcid":false,"given":"Christian","family":"B\u00e4umer","sequence":"additional","affiliation":[{"name":"Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), 45147 Essen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paul-Heinz","family":"Kramer","sequence":"additional","affiliation":[{"name":"Faculty of Physics, TU Dortmund University, 44227 Dortmund, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Theresa","family":"Steinmeier","sequence":"additional","affiliation":[{"name":"Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), 45147 Essen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefanie Schulze","family":"Schleithoff","sequence":"additional","affiliation":[{"name":"Faculty of Physics, TU Dortmund University, 44227 Dortmund, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5600-468X","authenticated-orcid":false,"given":"Stephan","family":"Tschirdewahn","sequence":"additional","affiliation":[{"name":"Department of Urology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Boris","family":"Hadaschik","sequence":"additional","affiliation":[{"name":"Department of Urology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Beate","family":"Timmermann","sequence":"additional","affiliation":[{"name":"Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), 45147 Essen, Germany"},{"name":"Faculty of Physics, TU Dortmund University, 44227 Dortmund, Germany"},{"name":"German Cancer Consortium (DKTK), 45147 Essen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e180039","DOI":"10.1001\/jamaoncol.2018.0039","article-title":"Effect of Standard vs Dose-Escalated Radiation Therapy for Patients With Intermediate-Risk Prostate Cancer: The NRG Oncology RTOG 0126 Randomized Clinical Trial","volume":"4","author":"Michalski","year":"2018","journal-title":"JAMA Oncol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1016\/j.ijrobp.2007.06.054","article-title":"Long-term results of the M. 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