PROstate Multicentre External beam radioTHErapy Using a Stereotactic boost: the PROMETHEUS study protocol

Richardson, Matthew; Sidhom, Mark; Gallagher, Sarah; Grand, M.; Pryor, David; Bucci, Joseph; Wilton, Lee; Arumugam, Sankar; Keats, Sarah; Martin, Jarad

doi:10.1186/s12885-018-4511-6

Cited by 16 publications

(12 citation statements)

References 27 publications

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“…Similarly with the increasing inclusion of the seminal vesicles in the target volume in recent trials will also further increase the dosimetric impact of these prostate tilts due to the elongation of the volume in the superior-inferior direction. 26 It can be seen that for both CTV and PTV the sphericity and CI are highly regular with very low variability. This would indicate that the patient population have very similar shaped prostates and that consistent planning outcomes are being achieved respectively.…”

Section: Discussionmentioning

confidence: 91%

Dosimetric impact of intrafraction rotations in stereotactic prostate radiotherapy: A subset analysis of the TROG 15.01 SPARK trial

Wolf

Nicholls

Hunter

et al. 2019

Radiotherapy and Oncology

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Background & Purpose Accurate delivery of radiotherapy is critical to achieve optimal treatment outcomes. Interfraction translational IGRT is now standard, and intrafraction motion management is becoming accessible. Some platforms can report both translational and rotational movements in real time. This study aims to quantify the dosimetric impact of observed intrafraction rotation of the prostate measured using monitoring software. Materials & Methods A dose grid resampling algorithm was used to model the dosimetric impact of prostate rotations for 20 patients on a SBRT prostate clinical trial. Translations were corrected before and during treatment, but rotations were not. Real time rotation data was acquired using KIM and a cumulative histogram analysis performed. Prostate volumes were rotated by the range of observed angles and used to calculate DVH data. Results The pitch axis had a higher range of observed rotations resulting in only 7 patients spending at least 90% of the beam on time across all fractions within rotation angles resulting in PTV D95%≥36Gy in this axis. The yaw and roll axes saw 17 and 15 patients respectively achieving this criterion. All but one of 20 patients exceeded CTV D98% ≥36Gy for all observed rotation angles. Conclusions Current CTV-PTV margins do not result in compromised CTV dose coverage due to inter and intrafraction prostate rotations in the absence of other uncertainties. Reduced PTV dosing is due to the extremely conformal treatment delivery but is unlikely to be clinically deleterious. Prostate standard IGRT should continue to focus on correcting any observed translational movements. Margin reduction could be explored in conjunction with other uncertainties. Highlights • Prostate intrafraction rotations are typically non-symmetrical about the pitch axis • Observed rotations resulted in reduced PTV dose coverage for many patients • CTV coverage was maintained for virtually all observed rotations • Existing SBRT CTV-PTV margins sufficient to account for intrafraction rotations

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Section: Discussionmentioning

confidence: 91%

Dosimetric impact of intrafraction rotations in stereotactic prostate radiotherapy: A subset analysis of the TROG 15.01 SPARK trial

Wolf

Nicholls

Hunter

et al. 2019

Radiotherapy and Oncology

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“…SBRT prostate clinical trial protocols specify the CTV to PTV margins to be used in treatment planning [19][20][21]. While there is no consensus for standardized margin values for prostate SBRT across all trials, clinical sites participating in a given trial should have positioning and immobilization techniques that meet the specified CTV-PTV margins in the study protocol.…”

Section: Discussionmentioning

confidence: 99%

“…A phase II study of prostate SBRT (35 Gy in five fractions) using volumetric modulated arc therapy and flattening free 10 MV photons, which specified CTV to PTV margins of 3-5 mm in each direction, found that the treatments were feasible and tolerated in an acute setting [19]. The PROMETHEUS study protocol, exploring the safety, efficacy, and feasibility of a two fraction SBRT boost, specifies a CTV to PTV margin of 5 mm everywhere except posterior where it is 3 mm [20]. The Novel Integration of New prostate radiation schedules with adJuvant Androgen deprivation (NINJA) clinical trial is a randomized study comparing two emerging SBRT regimens (a five fraction and a two fraction) for efficacy specifies a 3 mm uniform CTV to PTV expansion for SBRT treatments [21].…”

Section: Discussionmentioning

confidence: 99%

Preliminary Clinical Evaluation of Intrafraction Prostate Displacements for Two Immobilization Systems

Mostafaei

Dougherty

Hamilton

2020

Cureus

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Immobilization systems and their corresponding setup errors influence the clinical target volume to the planning target volume (CTV-PTV) margins, which is critical for hypofractionated prostate stereotactic body radiotherapy (SBRT). This preliminary study evaluates intrafraction prostate displacement for two immobilization systems (A and B). Six consecutive patients having localized prostate cancer and implanted prostate marker seeds were studied. Planar X-ray images were acquired pre-and post-treatment to find the intrafraction prostate displacement. The average absolute displacements (lateral, longitudinal, vertical) were 0.9 ± 0.4 mm, 1.7 ± 0.1 mm, 1.3 ± 0.3 mm (system A), and 0.5 ± 0.2 mm, 0.6 ± 0.1 mm, 0.8 ± 0.3 mm (system B), with average three-dimensional displacements of 2.6 ± 0.2 mm (system A) and 1.3 ± 0.2 mm (system B). The computed CTV-PTV margins (lateral, longitudinal, vertical) were 2.5 mm, 2.5 mm, 3.6 mm and 1.4 mm, 1.6 mm, 2.4 mm for systems A and B, respectively. This suggests that the immobilization system influences intrafraction prostate displacement and, therefore, the margins applied. However, the margins found for both systems are comparable to the margins used for hypofractionated prostate SBRT.

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“…The set-up for the primary planning CT was to be the same as for treatment (e.g., with or without IDC). Full technical details have been described previously (11).…”

Section: Methodsmentioning

confidence: 99%

“…A dose of 46 Gy in 23 daily fractions was prescribed using IMRT or VMAT with daily image guidance. Dose constraints for the EBRT component have been outlined previously (11). Following publication of the PROFIT and CHHIP hypofractionation studies, the protocol was amended in 2017 to allow an alternate EBRT fractionation schedule of 36 Gy in 12 daily fractions (13–15).…”

Section: Methodsmentioning

confidence: 99%

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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PROstate Multicentre External beam radioTHErapy Using a Stereotactic boost: the PROMETHEUS study protocol

Cited by 16 publications

References 27 publications

Dosimetric impact of intrafraction rotations in stereotactic prostate radiotherapy: A subset analysis of the TROG 15.01 SPARK trial

Dosimetric impact of intrafraction rotations in stereotactic prostate radiotherapy: A subset analysis of the TROG 15.01 SPARK trial

Preliminary Clinical Evaluation of Intrafraction Prostate Displacements for Two Immobilization Systems

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

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