Maximizing rectal dose sparing with hydrogel: A retrospective planning study

Paetkau, O.; Gagne, Isabelle; Pai, Howard; Lam, Jacqueline; Goulart, Jennifer; Alexander, Abraham

doi:10.1002/acm2.12566

Cited by 4 publications

(4 citation statements)

References 27 publications

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“…The use of hydrogel to inject connective tissue between the prostate and the rectum can effectively reduce rectal volume. [ 10 ] Due to the limitations of the study conditions, none of our subjects used similar techniques, so the rectal volume of the PODT group and the PMRT group increased significantly, which was also significantly higher than the data reported in other studies. [ 11 ] It may be related to the fact that external radiation increases the target area of radiation therapy and increases the risk of rectal injury.…”

Section: Discussionmentioning

confidence: 62%

Treating the primary in low burden metastatic prostate cancer

Luo¹,

Fu²,

Wang³

et al. 2020

Medicine

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On the basis of endocrine therapy for patients with low burden metastatic prostate cancer (LBMP), the clinical efficacy and quality of life were compared between prostate-only directed radiotherapy (PODT) and prostate and metastasis radiotherapy (PMRT). From November 2009 to November 2015, total 91 patients newly diagnosed with LBMP were retrospectively analyzed, of which 52 patients received PODT and 39 patients received PMRT. The biochemical failure free interval (IBF), prostate specific survival (PCSS), and overall survival (OS) time were compared between the 2 groups, and expanded prostate cancer index composite (EPIC) scale was used to evaluate the difference in quality of life between the 2 groups. The median IBF of the PODT group was 31 months, which was significantly lower than the 39 months of the PMRT group ( P < .05); the 5-year OS and PCSS were 58.9%, 65.3% in PODT group, and 58.9%, 71.79% in PMRT group, respectively. There was no significant between the 2 groups ( P > .05); the side effects of acute radiotherapy in PMRT group were significantly higher than PODT group ( P < .05), especially in bone marrow suppression and gastrointestinal reactions; The scores of urinary system function and intestinal system function in PMRT group were significantly higher than PODT group at the end of radiotherapy, 3 months after radiotherapy, and 6 months after radiotherapy ( P < .05). The score of sexual function in PMRT group was significantly lower than that in PODT group after radiotherapy ( P < .05), and higher than that in PORT group at other follow-up time points ( P < .05). The hormone function was decreased at each follow-up time point in 2 groups, and there was no significant difference between the 2 groups ( P > .05). Patients with LBMP receiving PMRT can improve IBF, but cannot increase PCSS and OS, and increase the incidence of acute radiation injury.

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Section: Discussionmentioning

confidence: 62%

Treating the primary in low burden metastatic prostate cancer

Luo¹,

Fu²,

Wang³

et al. 2020

Medicine

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“…Some of the methods described in this study are similar to the methods used in a previous paper. 26 However, different analysis has been applied to the data resulting in unique results and conclusions.…”

Section: Methodsmentioning

confidence: 99%

“…Rectal wall (RW) was used as an optimization structure as it has been shown to most effectively reduce the rectal dose when using SOH. 26 Similarly, optimization objectives were placed on PTV, CTV, bladder wall, penile bulb, and femoral heads. Treatment plans were deemed optimal once the plan evaluation objectives shown in Table 1 were reached with a plan normalization adjustment of less than AE0.5% following the final dose calculation.…”

Section: C | Treatment Planningmentioning

confidence: 99%

SpaceOAR© hydrogel rectal dose reduction prediction model: a decision support tool

Paetkau

Gagne

Alexander

2020

J Applied Clin Med Phys

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Prostate cancer external beam radiation therapy can result in toxicity due to organ at risk (OAR) dose, potentially impairing quality of life. A polyethylene glycol-based spacer, SpaceOAR© hydrogel (SOH), implanted between prostate gland and rectum may significantly reduce dose received by the rectum and hence risk of rectal toxicity. SOH implant is not equally effective in all patients. Determining patients in which the implant will offer most benefit, in terms of rectal dose reduction, allows for effective management of SOH resources. Several factors have been shown to be correlated with reduction in rectal dose including distance between rectum and planning treatment volume (PTV), volume of rectum in the PTV, and change in rectum volume pre-to post-SOH. Several of these factors along with other pre-SOH CT metrics were able to predict reduction in rectal dose associated with SOH implant. Rectal V55Gy metric, was selected as the dose level of interest in the context of 60 Gy in 20 fraction treatment plans. Models were produced to predict change in RV55Gy and pre-SOH hydrogel RV55Gy. These models offered R-squared between 0.81 and 0.88 with statistical significance in each model. Applying an ω 1 = 3% lower limit of pre-SOH RV55 Gy and an ω 2 = 3.5% lower limit on change in RV55 Gy, retained 60% of patients experiencing the largest rectal dose reduction from the hydrogel. This may offer a clinically useful tool in deciding which patients should receive SOH implant given limited resources. Predictive models, nomograms, and a workflow diagram were produced for clinical management of SOH implant. K E Y W O R D S decision support tool, linear modeling, rectal dose, SpaceOAR hydrogel 1 | INTRODUCTION Prostate is the most common cancer site in Canadian men excluding skin cancers, accounting for 20% of new cases each year and 10% of cancer deaths in men in 2018. 1 There exist many options for treatment including surgery, external beam radiotherapy (EBRT), and brachytherapy. Many patients choose EBRT as their treatment option, however, EBRT may result in rectal, urinary, and sexual toxicities due to irradiation of organs at risk (OARs) suchas the rectum, bladder, and penile bulb. 2 The rectum is the dose limiting organ in prostate EBRT due to its proximity to the prostate. 3,4 Products to create space between the rectum and the prostate and thus potentially reduce rectal toxicities during radiotherapy have been suggested. One such product is the Space-OAR© hydrogel (SOH) which is a polyethylene glycol-based product injected transperineally between the prostate and the rectum, increasing the space between the organs. This additional space allows for sparing of the rectum from high dose, which has ---

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“…At a minimum, typical dose constraints used in non-spacer patients should be easily achievable with placement of a spacer ( 21 ), and should ideally allow for safer dose escalation ( 64 ). One frequently employed strategy to aggressively manage rectal dose is to contour the spacer itself as part of the rectal contour, although retrospective data suggest that this approach may not yield optimal treatment plans ( 65 ) ( Figure 6 ).…”

Section: Assessment Of Spacer Placement and Planning Considerationsmentioning

confidence: 99%

Rationale for Utilization of Hydrogel Rectal Spacers in Dose Escalated SBRT for the Treatment of Unfavorable Risk Prostate Cancer

et al. 2022

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In this review we outline the current evidence for the use of hydrogel rectal spacers in the treatment paradigm for prostate cancer with external beam radiation therapy. We review their development, summarize clinical evidence, risk of adverse events, best practices for placement, treatment planning considerations and finally we outline a framework and rationale for the utilization of rectal spacers when treating unfavorable risk prostate cancer with dose escalated Stereotactic Body Radiation Therapy (SBRT).

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Maximizing rectal dose sparing with hydrogel: A retrospective planning study

Cited by 4 publications

References 27 publications

Treating the primary in low burden metastatic prostate cancer

Treating the primary in low burden metastatic prostate cancer

SpaceOAR© hydrogel rectal dose reduction prediction model: a decision support tool

Rationale for Utilization of Hydrogel Rectal Spacers in Dose Escalated SBRT for the Treatment of Unfavorable Risk Prostate Cancer

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