scholarly journals Biologically Effective Dose and Rectal Bleeding in Definitive Proton Therapy for Prostate Cancer

2021 ◽  
Author(s):  
Ronik S. Bhangoo ◽  
Molly M. Petersen ◽  
Gabriella F. Bulman ◽  
Carlos E. Vargas ◽  
Cameron S. Thorpe ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Rectal Bleeding ◽  
Univariate Analysis ◽  
Youden Index ◽  
Bleeding Events ◽  
Conventional Fractionation ◽  
Rectal Dose ◽  
Multivariate Logistic Model ◽  
Clinically Significant

Abstract Purpose and Objectives With increasing use of hypofractionation and extreme hypofractionation for prostate cancer, rectal dose-volume histogram (DVH) parameters that apply across dose fractionations may be helpful for treatment planning in clinical practice. We present an exploratory analysis of biologically effective rectal dose (BED) and equivalent rectal dose in 2 Gy fractions (EQD2) for rectal bleeding in patients treated with proton therapy across dose fractionations. Materials and Methods From 2016 to 2018, 243 patients with prostate cancer were treated with definitive proton therapy. Rectal DVH parameters were obtained from treatment plans, and rectal bleeding events were recorded. The BED and EQD2 transformations were applied to each rectal DVH parameter. Univariate analysis using logistic regression was used to determine DVH parameters that were significant predictors of grade ≥ 2 rectal bleeding. Youden index was used to determine optimum cutoffs for clinically meaningful DVH constraints. Stepwise model-selection criteria were then applied to fit a “best” multivariate logistic model for predicting Common Terminology Criteria for Adverse Events grade ≥ 2 rectal bleeding. Results Conventional fractionation, hypofractionation, and extreme hypofractionation were prescribed to 117 (48%), 84 (34%), and 42 (17.3%) patients, respectively. With a median follow-up of 20 (2.5-40) months, 10 (4.1%) patients experienced rectal bleeding. On univariate analysis, multiple rectal DVH parameters were significantly associated with rectal bleeding across BED, EQD2, and nominal doses. The BED volume receiving 55 Gy > 13.91% was found to be statistically and clinically significant. The BED volume receiving 55 Gy remained statistically significant for an association with rectal bleeding in the multivariate model (odds ratio, 9.81; 95% confidence interval, 2.4-40.5; P = .002). Conclusion In patients undergoing definitive proton therapy for prostate cancer, dose to the rectum and volume of the rectum receiving the dose were significantly associated with rectal bleeding across conventional fractionation, hypofractionation, and extreme hypofractionation when using BED and EQD2 transformations.

scholarly journals Preliminary analysis of prostate positional displacement using hydrogel spacer during the course of proton therapy for prostate cancer

2020 ◽  
Author(s):  
Hiroki Sato ◽  
Takahiro Kato ◽  
Tomoaki Motoyanagi ◽  
Kimihiro Takemasa ◽  
Yuki Narita ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Rectal Dose ◽  
Prostate Motion ◽  
Significant Difference ◽  
Risk Prostate Cancer ◽  
Bony Anatomy ◽  
Study Population ◽  
Planning Ct ◽  
Anterior Posterior

Abstract In recent years, a novel technique has been employed to maintain a distance between the prostate and the rectum by transperineally injecting a hydrogel spacer (HS). However, the effect of HS on the prostate positional displacement is poorly understood, despite its stability with HS in place. In this study, we investigated the effect of HS insertion on the interfraction prostate motion during the course of proton therapy (PT) for Japanese prostate cancer patients. The study population consisted of 22 cases of intermediate-risk prostate cancer with 11 cases with HS insertion and 11 cases without HS insertion. The irradiation position and preparation were similar for both groups. To test for reproducibility, regular confirmation computed tomography (RCCT) was done four times during the treatment period, and five times overall [including treatment planning CT (TPCT)] in each patient. Considering the prostate position of the TPCT as the reference, the change in the center of gravity of the prostate relative to the bony anatomy in the RCCTs of each patient was determined in the left–right (LR), superior–inferior (SI) and anterior–posterior (AP) directions. As a result, no significant difference was observed across the groups in the LR and SI directions. Conversely, a significant difference was observed in the AP direction (P < 0.05). The proportion of the 3D vector length ≤5 mm was 95% in the inserted group, but 55% in the non-inserted group. Therefore, HS is not only effective in reducing rectal dose, but may also contribute to the positional reproducibility of the prostate.

Proton therapy for prostate cancer: An analysis of rectal toxicity outcomes at University of Florida Proton Therapy Institute (UFPTI).

2014 ◽  
Vol 32 (4_suppl) ◽  
pp. 161-161
Author(s):  
Rovel J. Colaco ◽  
Bradford S. Hoppe ◽  
Randal H. Henderson ◽  
Romaine Charles Nichols ◽  
Christopher G. Morris ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Dose ◽  
Proton Therapy ◽  
Rectal Bleeding ◽  
Treatment Technique ◽  
Rectal Toxicity ◽  
University Of Florida ◽  
Increased Risk ◽  
Potential Risk Factors ◽  
Grade 3

161 Background: We aimed to characterize gastrointestinal effects of proton therapy (PT) in patients treated for prostate cancer, identify factors associated with rectal bleeding (RB), and compare RB between patients on investigational protocols (IP) versus outcome tracking protocols (OTP). Methods: 1,290 patients treated consecutively with PT between August 2006 and June 2010 were studied. Pre-existing potential risk factors for RB (hemorrhoids, diabetes, aspirin, other anticoagulants) were recorded. Common terminology criteria for adverse events (CTCAE version 4.0) were used to grade toxicity. Median follow up was 3.5 years. Results: The majority (94.6%) of Grade 2 or higher gastrointestinal toxicity (GR2+) events after PT were rectal bleeding. GR1 RB occurred in 390 (30.2%) of patients, including those requiring no prescription intervention (82.6%) and those placed on a vitamin A regimen (16.3%). GR2 RB occurred in 14.7% of patients, including patients requiring prescription rectal suppositories (9.5%), cautery (4.9%), or hyperbaric oxygen (0.3%). Grade 3 (GR3) occurred in 0.8% of patients, including those requiring transfusion (0.6%) or colostomy (0.1%). Multivariate analyses showed that pretreatment daily aspirin (p=0.03), other anticoagulation (p=0.001), and the volume of rectum exposed to radiation dose levels (V70) (<.0001) were associated with an increased risk of Gr2+RB. Patients treated on investigational protocols (IP) had similar toxicity rates as those treated on an outcomes tracking protocol (OTP). Reduced rectal toxicity was noted in latter years of the study, which correlated with changes in treatment technique, pretreatment evaluation, and post-treatment supportive care regimens. Conclusions: PT was associated with low rates of GI toxicity, the most common toxicity being transient RB. GR2+RB is strongly associated with patient use of aspirin, other anti-coagulation and radiation dose volume parameters.

887 Impact of mean rectal dose on late rectal bleeding following conformal radiotherapy for prostate cancer: dose volume effect

2003 ◽  
Vol 1 (5) ◽  
pp. S267
Author(s):  
A. Zapatero ◽  
F. Garcia-Vicente ◽  
I. Modolell ◽  
P. Alcantara ◽  
A. Floriano ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Rectal Bleeding ◽  
Conformal Radiotherapy ◽  
Volume Effect ◽  
Rectal Dose ◽  
Dose Volume

Impact of mean rectal dose on late rectal bleeding after conformal radiotherapy for prostate cancer: Dose–volume effect

2004 ◽  
Vol 59 (5) ◽  
pp. 1343-1351 ◽  
Author(s):  
Almudena Zapatero ◽  
Feliciano García-Vicente ◽  
Ignasi Modolell ◽  
Pino Alcántara ◽  
Alejandro Floriano ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Rectal Bleeding ◽  
Conformal Radiotherapy ◽  
Volume Effect ◽  
Rectal Dose ◽  
Dose Volume

scholarly journals Hydrogel Spacer Reduces Rectal Dose during Proton Therapy for Prostate Cancer: A Dosimetric Analysis

2019 ◽  
Vol 5 (4) ◽  
pp. 23-31 ◽  
Author(s):  
Praveen Polamraju ◽  
Alexander F. Bagley ◽  
Tyler Williamson ◽  
X. Ronald Zhu ◽  
Steven J. Frank
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Rectal Wall ◽  
Anterior Rectal Wall ◽  
Linear Regression Models ◽  
Intensity Modulated Proton Therapy ◽  
Rectal Dose ◽  
Before And After ◽  
Biodegradable Hydrogel ◽  
Dosimetric Analysis

Abstract Purpose: Proton therapy for prostate cancer may reduce bowel dose and risk of bowel symptoms relative to photon-based methods. Here, we determined the effect of using a biodegradable, injectable hydrogel spacer on rectal dose on plans for treating prostate cancer with intensity-modulated proton therapy (IMPT) or passive scattering proton therapy (PSPT). Materials and Methods: Pairs of IMPT and PSPT plans for 9 patients were created from fused computed tomography/magnetic resonance imaging scans obtained before and after spacer injection. Calculated values of rectal V40, V60, V70, V80, and maximum dose (Dmax) were compared with Wilcoxon signed rank tests. Displacements at the base (BP), midgland (MP), and apex (AP) of the prostate relative to the anterior rectal wall with the spacer in place were averaged for each patient and correlated with V70 by using linear regression models. Results: The presence of a spacer reduced all dosimetric parameters for both PSPT and IMPT, with the greatest difference in V70, which was 81.1% lower for PSPT-with-spacer than for IMPT-without-spacer. Median displacements at BP, MP, and AP were 12 mm (range 7-19), 2 mm (range 0-4), and 1 mm (range 0-5) without the spacer and 19 mm (range 12-23), 10 mm (range 8-16), and 7 mm (range 2-12) with the spacer. Modest linear trends were noted between rectal V70 and displacement for IMPT-with-spacer and PSPT-with-spacer. When displacement was ≥8 mm, V70 was ≤5.1% for IMPT-with-spacer and PSPT-with-spacer. Conclusion: Use of biodegradable hydrogel spacers for prostate cancer treatment provides a significant reduction of radiation dose to the rectum with proton therapy. Significant reductions in rectal dose occurred in both PSPT and IMPT plans, with the greatest reduction for IMPT-with-spacer relative to PSPT alone. Prospective studies are ongoing to assess the clinical impact of reducing rectal dose with hydrogel spacers.

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