Refinement &amp; validation of rectal wall dose volume objectives for prostate hypofractionation in 20 fractions

Sanguineti, Giuseppe; Faiella, A.; Farneti, Alessia; D’Urso, Pasqualina; Fuga, Valentina; Olivieri, Michela; Giannarelli, Diana; Marzi, Simona; Iaccarino, Giuseppe; Landoni, V.

doi:10.1016/j.ctro.2020.01.006

Cited by 5 publications

(7 citation statements)

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“…In an earlier study of conventionally fractionated treatment for prostate cancer, V50 Gy was found to be the most significant factor associated with chronic rectal toxicity [ 16 ]. Similarly, a more-recent study of hypofractionation found that a rectal wall V50 Gy ≥ 26% would predict for increased risk of rectal bleeding (along with V32 Gy ≥ 50% and V60 Gy ≥ 10%) [ 17 ]. The above 2 studies were done in the context of photon radiation.…”

Section: Discussionmentioning

confidence: 99%

“…Both increasing the radiation dose to the rectum and increasing the volume of the rectum receiving the dose have been associated with higher rates of rectal bleeding [ 16 ]. Limited reports have been published specifically analyzing rectal dose-volume histogram (DVH) parameters for rectal bleeding using hypofractionated radiation regimens (in particular with proton therapy) [ 17 , 18 ]. Moreover, these data do not apply across dose fractionations commonly used in modern treatment regimens.…”

Section: Introductionmentioning

confidence: 99%

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

Bhangoo

Petersen

Bulman

et al. 2022

International Journal of Particle Therapy

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Bhangoo

Petersen

Bulman

et al. 2022

International Journal of Particle Therapy

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“…Since toxicity is related to dose to the rectal wall and not its content, we evaluated the methods on the rectal wall. Since the inner wall is not seen on CT scans, we assumed 3 mm wall thickness, as in Sanguineti et al (2020).…”

Section: Methodsmentioning

confidence: 99%

An organ deformation model using Bayesian inference to combine population and patient-specific data

Rørtveit

Hysing²,

Stordal³

et al. 2023

Phys. Med. Biol.

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Objective: Organ deformation models have the potential to improve delivery and reduce toxicity of radiotherapy, but existing data-driven motion models are based on either patient-specific or population data. We propose to combine population and patient-specific data using a Bayesian framework. Our goal is to accurately predict individual motion patterns while using fewer scans than previous models. Approach: We have derived and evaluated two Bayesian deformation models. The models were applied retrospectively to the rectal wall from a cohort of prostate cancer patients. These patients had repeat CT scans evenly acquired throughout radiotherapy. Each model was used to create coverage probability matrices (CPMs). The spatial correlations between these estimated CPMs and the ground truth, derived from independent scans of the same patient, were calculated.\\ Main results: Spatial correlation with ground truth were significantly higher for the Bayesian deformation models than both patient-specific and population-derived models with 1, 2 or 3 patient-specific scans as input. Statistical motion simulations indicate that this result will also hold for more than 3 scans. \\ Significance: The improvement over previous models means that fewer scans per patient are needed to achieve accurate deformation predictions. The models have applications in robust radiotherapy planning and evaluation, among others.

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“…Ideally, this could result in enhanced tumor control and a low incidence rate of toxicity. In spite of advancements in technology and a favorable radiobiological perspective, the rectum continues to be a dose-limiting organ in prostate external beam radiotherapy, including MHRT [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…A number of studies have demonstrated a relationship between parameters derived from the dose-volume histogram (DVH) and the incidence of rectal toxicity. Nevertheless, the available literature on the setting of MHRT and its association with late rectal toxicity is scarce, as evidenced by the limited data exploring the correlation between specific dose/volume metrics and late rectal adverse events [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. In addition, various schedules of MHRT have been examined, and different parameters related to dose volume have been evaluated.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive 3DCRT Hypofractionated Radiotherapy Schedule for Localized Prostate Adenocarcinoma in the Era of IMRT: Dosimetric and Endoscopic Analysis

Kougioumtzopoulou,

Syrigos,

Zygogianni

et al. 2024

Cancers

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Background: Moderate hypofractionated radiotherapy (MHRT) has emerged as the preferred treatment modality for localized prostate cancer based on randomized controlled studies regarding efficacy and toxicity using contemporary radiotherapy techniques. In the setting of MHRT, available data on dosimetric parameters and late rectal toxicity are limited. Aim: To present the effects of MHRT on late rectal toxicity while conducting an extensive dosimetric analysis in conjunction with rectoscopy results. Methods: This is a prospective study including patients with intermediate-risk prostate adenocarcinoma. All patients were treated with MHRT 44 Gy in 16 fractions to the seminal vesicles and to the prostate, followed by a sequential boost to the prostate alone of 16.5 Gy in 6 fractions delivered with three-dimensional conformal radiation therapy (3DCRT). Acute and late toxicity were assessed. Endoscopy was performed at baseline, every 3 months post-therapy for the first year, and every 6 months for the year after. The Vienna Rectoscopy Score (VRS) was used to assess rectal mucosal injury related to radiotherapy. Dosimetric analysis for the rectum, rectal wall, and its subsegments (upper, mid, and low 1/3) was performed. Results: Between September 2015 and December 2019, 20 patients enrolled. Grade 1 late gastrointestinal toxicity occurred in 10% of the patients, whereas 5% had a grade ≥2. Twelve months post radiotherapy: 4 (20%) patients had VRS 1; 2 (10%) patients had VRS 2; 1(5%) patient had VRS 3. 24 months post radiotherapy, VRS 1 was observed in 4 patients (20%) and VRS 2 in 3 (15%) patients. The dosimetric analysis demonstrated noticeable variations between the rectum, rectal wall, and rectal wall subsegments. The dosimetric analysis of the rectum, rectal wall, and its mid and low segments with respect to rectoscopy findings showed that the higher dose endpoints V52.17Gy and V56.52Gy are associated with rectal mucosal injury. Conclusions: A thorough delineation of the rectal wall and its subsegments, together with the dosimetric analysis of these structures, may reduce late rectal toxicity. Dosimetric parameters such as V52.17Gy and V56.52Gy were identified to have a significant impact on rectal mucosal injury; additional dose endpoint validation and its relation to late GI toxicity is needed.

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Refinement & validation of rectal wall dose volume objectives for prostate hypofractionation in 20 fractions

Cited by 5 publications

References 46 publications

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

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

An organ deformation model using Bayesian inference to combine population and patient-specific data

Comprehensive 3DCRT Hypofractionated Radiotherapy Schedule for Localized Prostate Adenocarcinoma in the Era of IMRT: Dosimetric and Endoscopic Analysis

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