TY  - JOUR
AU  - Ahmad Khalil, Dalia
AU  - Wulff, Jörg
AU  - Jazmati, Danny
AU  - Geismar, Dirk
AU  - Bäumer, Christian
AU  - Kramer, Paul-Heinz
AU  - Steinmeier, Theresa
AU  - Schleithoff, Stefanie Schulze
AU  - Tschirdewahn, Stephan
AU  - Hadaschik, Boris
AU  - Timmermann, Beate
TI  - 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.
JO  - Current oncology
VL  - 30
IS  - 1
SN  - 1198-0052
CY  - Toronto, Ontario
PB  - Multimed
M1  - DKFZ-2023-00130
SP  - 758 - 768
PY  - 2023
AB  - 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).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× weekly to prostate + 1 cm of the seminal vesicle, and 60 Gy/2 Gy/5× 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).For ERB plans compared with non-ERB, the reductions were 8.51 ± 5.25 Gy (RBE) (p = 0.000) and 15.76 ± 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 ≥ 2, necrosis or stenosis, and late rectal toxicity ≥ 3) when using the ERB.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.
KW  - dose-escalated radiation therapy (Other)
KW  - endorectal balloon (Other)
KW  - hypofractionated radiation therapy (Other)
KW  - intensity-modulated therapy (Other)
KW  - prostate cancer (Other)
KW  - proton therapy (Other)
LB  - PUB:(DE-HGF)16
C6  - pmid:36661707
C2  - pmc:PMC9857887
DO  - DOI:10.3390/curroncol30010058
UR  - https://inrepo02.dkfz.de/record/212411
ER  -