Rectal protection in prostate stereotactic radiotherapy: a retrospective exploratory analysis of two rectal displacement devices

Wilton, Lee; Richardson, Matthew; Keats, Sarah; Legge, Kimberley; Hanlon, Mary‐Claire; Arumugam, Sankar; Hunter, Perry; Evans, Tiffany‐Jane; Sidhom, Mark; Martin, Jarad

doi:10.1002/jmrs.238

Cited by 12 publications

(13 citation statements)

References 24 publications

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“…This may reflect more of a self-limiting, peripheral neuropathy rather than mucosal effects. Regarding the method of rectal displacement we have previously reported that SpaceOAR and Rectafix provide similar dosimetric advantages in terms of rectal sparing (19). SpaceOAR was associated with less discomfort and has the added advantage of being in situ for the fractionated component of treatment; however, the additional cost is not routinely covered in Australia currently and there is a small risk of inadequate separation.…”

Section: Discussionmentioning

confidence: 96%

Phase 2 Multicenter Study of Gantry-Based Stereotactic Radiotherapy Boost for Intermediate and High Risk Prostate Cancer (PROMETHEUS)

et al. 2019

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Objectives: To report feasibility, early toxicity, and PSA kinetics following gantry-based, stereotactic radiotherapy (SBRT) boost within a prospective, phase 2, multicenter study (PROMETHEUS: ACTRN12615000223538). Methods: Patients were treated with gantry-based SBRT, 19–20 Gy in two fractions delivered 1 week apart, followed by conventionally fractionated IMRT (46 Gy in 23 fractions). The study mandated MRI fusion for RT planning, rectal displacement, and intrafraction image guidance. Toxicity was prospectively graded using the Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4). Results: Between March 2014 and July 2018, 135 patients (76% intermediate, 24% high-risk) with a median age of 70 years (range 53–81) were treated across five centers. Short course (≤6 months) androgen deprivation therapy (ADT) was used in 36% and long course in 18%. Rectal displacement method was SpaceOAR in 59% and Rectafix in 41%. Forty-two and ninety-three patients were treated at the 19 Gy and 20 Gy dose levels, respectively. Median follow-up was 24 months. Acute grade 2 gastrointestinal (GI) and urinary toxicity occurred in 4.4 and 26.6% with no acute grade 3 toxicity. At 6, 12, 18, 24, and 36 months post-treatment the prevalence of late grade ≥2 gastrointestinal toxicity was 1.6, 3.7, 2.2, 0, and 0%, respectively, and the prevalence of late grade ≥2 urinary toxicity was 0.8, 11, 12, 7.1, and 6.3%, respectively. Three patients experienced grade 3 late toxicity at 12 to 18 months which subsequently resolved to grade 2 or less. For patients not receiving ADT the median PSA value pre-treatment was 7.6 ug/L (1.1–20) and at 12, 24, and 36 months post-treatment was 0.86, 0.36, and 0.20 ug/L. Conclusions: Delivery of a gantry-based SBRT boost is feasible in a multicenter setting, is well-tolerated with low rates of early toxicity and is associated with promising PSA responses. A second transient peak in urinary toxicity was observed at 18 months which subsequently resolved. Follow-up is ongoing to document late toxicity, long-term patient reported outcomes, and tumor control with this approach.

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Section: Discussionmentioning

confidence: 96%

Phase 2 Multicenter Study of Gantry-Based Stereotactic Radiotherapy Boost for Intermediate and High Risk Prostate Cancer (PROMETHEUS)

et al. 2019

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“…For treatment mDSS, the proportion between the number of treatment options and the decision support tools remains somewhat skewed. Nguyen et al (2009)[50] suggested 15 different combinations of treatment options, and this did not include the use of rectal displacement devices [65, 66] or proton therapy. The treatment mDSS that were found by the current study primarily involved RT, including treatment plan selection [46], proton compared to photon therapy [49], SBRT compared to IMRT [43], and the use of an implantable rectum spacer in EBRT [47].…”

Section: Discussionmentioning

confidence: 99%

Decision Support Systems in Prostate Cancer Treatment: An Overview

Wijk

Halilaj

Limbergen

et al. 2019

BioMed Research International

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Background. A multifactorial decision support system (mDSS) is a tool designed to improve the clinical decision-making process, while using clinical inputs for an individual patient to generate case-specific advice. The study provides an overview of the literature to analyze current available mDSS focused on prostate cancer (PCa), in order to better understand the availability of decision support tools as well as where the current literature is lacking. Methods. We performed a MEDLINE literature search in July 2018. We divided the included studies into different sections: diagnostic, which aids in detection or staging of PCa; treatment, supporting the decision between treatment modalities; and patient, which focusses on informing the patient. We manually screened and excluded studies that did not contain an mDSS concerning prostate cancer and study proposals. Results. Our search resulted in twelve diagnostic mDSS; six treatment mDSS; two patient mDSS; and eight papers that could improve mDSS. Conclusions. Diagnosis mDSS is well represented in the literature as well as treatment mDSS considering external-beam radiotherapy; however, there is a lack of mDSS for other treatment modalities. The development of patient decision aids is a new field of research, and few successes have been made for PCa patients. These tools can improve personalized medicine but need to overcome a number of difficulties to be successful and require more research.

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“…Hydrogel spacer use in prostate SBRT was documented as early as 2013 by Alongi et al and continues to represent a growing proportion of SpaceOAR utilization [ 11 , 24 , 25 ]. Yet as of this study, the only published phase III randomized prostate hydrogel data were obtained in the conventionally fractionated setting [ 22 ].…”

Section: Discussionmentioning

confidence: 99%

A novel model to correlate hydrogel spacer placement, perirectal space creation, and rectum dosimetry in prostate stereotactic body radiotherapy

et al. 2018

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BackgroundThe SpaceOAR hydrogel is employed to limit rectal radiation dose during prostate radiotherapy. We identified a novel parameter – the product of angle θ and hydrogel volume – to quantify hydrogel placement. This parameter predicted rectum dosimetry and acute rectal toxicity in prostate cancer patients treated with stereotactic body radiotherapy to 36.25 Gy in 5 fractions.MethodsTwenty men with low- and intermediate-risk prostate cancer underwent hydrogel placement from 2015 to 2017. Hydrogel symmetry was assessed on the CT simulation scan in 3 axial slices (midgland, 1 cm above midgland, 1 cm below midgland). Two novel parameters quantifying hydrogel placement – hydrogel volume and angle θ formed by the prostate, hydrogel, and rectum – were measured, and the normalized product of θ and hydrogel volume calculated. These were then correlated with perirectal distance, rectum maximum 1–3 cc point doses (rDmax 1–3 cc), and rectum volumes receiving 80–95% of the prescription dose (rV80–95%). Acute rectal toxicity was recorded per RTOG criteria.ResultsIn 50% of patients, hydrogel placement was symmetric bilaterally to within 1 cm of midline in all three CT simulation scan axial slices. Lateral hydrogel asymmetry < 2 cm in any one axial slice did not affect rectum dosimetry, but absence of hydrogel in the inferior axial slice resulted in a mean increase of 171 cGy in the rDmax 1 cc (p < 0.005). The perirectal distance measured at prostate midgland, midline (mean 9.1 ± 4.3 mm) correlated strongly with rV95 (R2 0.6, p < 0.001). The mean hydrogel volume and θ were 10.3 ± 4.5 cc and 70 ± 49°, respectively. Perirectal distance, rV95 and rDmax 1 cc correlated with hydrogel angle θ (p < 0.01), and yet more strongly with the novel metric θ*hydrogel volume (p < 0.001). With a median follow up of 14 months, no rectal toxicity >grade 2 was observed. Low grade rectal toxicity was observed in a third of men and resolved within 1 month of SBRT. Men who had these symptoms had higher rDmax 1 cc and smaller θ*hydrogel volume measurements.ConclusionsOptimal hydrogel placement occurs at prostate midgland, midline. The novel parameter θ*hydrogel volume describes a large proportion of rectum dosimetric benefit derived from hydrogel placement, and can be used to assess the learning curve phenomenon for hydrogel placement.

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Rectal protection in prostate stereotactic radiotherapy: a retrospective exploratory analysis of two rectal displacement devices

Cited by 12 publications

References 24 publications

Phase 2 Multicenter Study of Gantry-Based Stereotactic Radiotherapy Boost for Intermediate and High Risk Prostate Cancer (PROMETHEUS)

Phase 2 Multicenter Study of Gantry-Based Stereotactic Radiotherapy Boost for Intermediate and High Risk Prostate Cancer (PROMETHEUS)

Decision Support Systems in Prostate Cancer Treatment: An Overview

A novel model to correlate hydrogel spacer placement, perirectal space creation, and rectum dosimetry in prostate stereotactic body radiotherapy

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