scholarly journals Dosimetric Feasibility of Moderately Hypofractionated/dose Escalated Radiation Therapy for Localised Prostate Cancer With Intensity-modulated Proton Beam Therapy Using Simultaneous Integrated Boost (SIB-IMPT) and Impact of Hydrogel Prostate-rectum Spacer

2021 ◽  
Author(s):  
Dalia Ahmad Khalil ◽  
Danny Jazmati ◽  
Dirk Geismar ◽  
Jörg Wulff ◽  
Christian Bäumer ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Therapy ◽  
Seminal Vesicle ◽  
Proton Beam ◽  
Proton Beam Therapy ◽  
Simultaneous Integrated Boost ◽  
Intensity Modulated ◽  
Spacer Group ◽  
Rectal Volume ◽  
Integrated Boost

Abstract Purpose: To examine the dosimetric feasibility of hypofractionated/dose escalated radiation therapy in patients with localized prostate carcinoma using simultaneous integrated boost intensity-modulated proton beam therapy (SIB-IMPT) in absence or presence of prostate-rectum spacer. Methods: IMPT technique was implemented in 23 patients with intermediate- and high-risk prostate cancer treated at West German Proton Therapy Centre from March 2016 till June 2018, using SIB technique prescribing 60 GyRBE and 72 GyRBE in 30 fractions to PTV1 (prostate and seminal vesicle) and PTV2 boost (prostate and proximal seminal vesicle), respectively. In 15 patients, a transperineal injection of hydrogel was applied prior to radiotherapy to increase the distance between prostate and rectum. Planning and all treatments were performed with a 120 ml fluid-filled endorectal balloon customised daily for each patient. For each patient, 2 lateral IMPT beams were implemented taking a field-specific range uncertainty (RU) into account. Dose volume histograms (DVH) were analyzed for PTV2, PTV2 with range uncertainty margin (PTV2RU), rectum, bladder, right/left femoral heads, and penile bulb. For late rectal toxicities, the normal tissue complication probabilities (NTCP) were calculated using different biological models. A DVH- and NTCP-based dosimetric comparison was carried out between non-spacer and spacer groups. Results: For the 23 patients, high-quality plans could be achieved for target volume and for other organs at risk (OARs). For PTV2, the V107% was 0% and the Dmax did not exceed 106.2% of the prescribed dose. The volume PTV2RU covered by 95% of the dose ranged from 96.16- 99.95%. The conformality index (CI) for PTV2RU was 1.12±0.057 and the homogeneity index (HI) was 1.04±0.014. Rectum Dmax and rectal volume receiving 73 to 50 Gy could be further reduced for the spacer-group. Significant reductions in mean and median rectal NTCPs (stenosis/necrosis, late rectal bleeding ≥ 2, and late rectal toxicities ≥ 3) were predicted for the spacer group in comparison to the non-spacer group. Conclusion: Hypofractionated/dose escalated radiotherapy with SIB-IMPT is dosimetrically feasible. Further reduction of the rectal volumes receiving high and medium dose levels (73 -50 Gy) and rectal NTCP could be achieved through injection of spacers between rectum and prostate.

scholarly journals Intensity-Modulated Radiation Therapy with Simultaneous Integrated Boost for Clinically Node-Positive Prostate Cancer: A Single-Institutional Retrospective Study

Cancers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 3868
Author(s):  
Masahiro Onishi ◽  
Hidemasa Kawamura ◽  
Kazutoshi Murata ◽  
Tatsuro Inoue ◽  
Hiroto Murata ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Therapy ◽  
Intensity Modulated Radiation Therapy ◽  
Simultaneous Integrated Boost ◽  
Relapse Free Survival ◽  
Free Survival ◽  
Intensity Modulated ◽  
Node Positive ◽  
Integrated Boost ◽  
Clinically Node Positive

This study aimed to evaluate clinical outcomes and the toxicity of intensity-modulated radiation therapy with simultaneous integrated boost (SIB-IMRT) combined with androgen-deprivation therapy for clinically node-positive (cN1) prostate cancer. We retrospectively analyzed 97 patients with cN1 prostate cancer who received SIB-IMRT between June 2008 and October 2017 at our hospital. The prescribed dosages delivered to the prostate and seminal vesicle, elective node area, and residual lymph nodes were 69, 54, and 60 Gy in 30 fractions, respectively. Kaplan–Meier analysis was used to determine 5-year biochemical relapse-free survival (bRFS), relapse-free survival (RFS), overall survival (OS), and prostate cancer-specific survival (PCSS). Toxicity was evaluated using the Common Terminology Criteria for Adverse Events ver. 4.0. Over a median follow-up duration of 60 months, the 5-year bRFS, RFS, OS, and PCSS were 85.1%, 88.1%, 92.7% and 95.0%, respectively. Acute Grade 2 genito-urinary (GU) and gastro-intestinal (GI) toxicities were observed in 10.2% and 2.1%, respectively, with no grade ≥3 toxicities being detected. The cumulative incidence rates of 5-year Grade ≥2 late GU and GI toxicities were 4.7% and 7.4%, respectively, with no Grade 4 toxicities being detected. SIB-IMRT for cN1 prostate cancer demonstrated favorable 5-year outcomes with low incidences of toxicity.

scholarly journals 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

2021 ◽  
Author(s):  
Dalia Ahmad Khalil ◽  
Jörg Wulff ◽  
Danny Jazmati ◽  
Dirk Geismar ◽  
Christian Bäumer ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cancer Patients ◽  
Seminal Vesicle ◽  
Proton Beam ◽  
Proton Beam Therapy ◽  
Rectal Toxicity ◽  
P Values ◽  
Intensity Modulated ◽  
Late Rectal Toxicity ◽  
Dose Levels

Abstract BackgroundThe aim of this study is to examine the dosimetric influence of endorectal balloons (ERB) in rectal sparing in prostate cancer patients with implanted hydrogel rectum spacers treated with dose escalated/hypofractionated intensity modulated proton beam therapy (IMPT). MethodsTen patients with localised prostate cancer included in the ProRegPros study and treated at our centre were invastigated in this study. All patients underwent a placement of hydrogel rectum spacers before planning. Two planning CTs (with and without 120 cm3 fluid-filled ERB) were acquired for each patient. Dose prescription was set according to the used simultaneous integrated boost strategy with 72 Gray (Gy)/2.4 Gy/5 x weekly to prostate+1 cm of the seminal vesicle, and 60 Gy/2 Gy/5 x weekly to prostate+2 cm of the seminal vesicle. Planning with two lateral-opposed IMPT beams was performed in both CTs. Rectal dosimetry values including dose-volume statistics and normal tissue complication probability (NTCP) in both plans were compared (non-ERB plans vs. ERB plans).ResultsFor ERB plans compared to non-ERB, the reductions were 8.51 ± 5.25 Gy (RBE) (p= 0.000) and 15.76 ± 11.11Gy (P= 0.001) for the mean and the median rectal dose, respectively. No significant reductions in rectal volumes receiving high dose levels were found. The use of ERB resulted in significant reduction in rectal volume 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. For the anterior rectum, no differences between ERB and non-ERB plans were observed. For the posterior rectum, ERB reduced rectal volumes received 30 Gy (RBE), 20 Gy (RBE), and 10 Gy (RBE) with P values of 0.019, 0.003, and 0.001, respectively. No significant reductions in mean or median rectal toxicity (Late rectal bleeding ≥2, necrosis/stenosis, and Late rectal toxicity ≥ 3) were observed when using the ERB according to NTCP models.ConclusionThe ERB reduced rectal volumes exposed to intermediate/low dose levels. However, no significant reduction in rectal volumes receiving high/intermediate doses could be observed. No benefit but also no disadvantage of the ERB for late rectal toxicity was found according to available NTCP models.

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