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Poon DMC, Yuan J, Wong OL, Yang B, Tse MY, Lau KK, Chiu ST, Chiu PKF, Ng CF, Chui KL, Kwong YM, Ma WK, Cheung KY, Chiu G, Yu SK. One-year clinical outcomes of MR-guided stereotactic body radiation therapy with rectal spacer for patients with localized prostate cancer. World J Urol 2024; 42:97. [PMID: 38393414 PMCID: PMC10891188 DOI: 10.1007/s00345-024-04784-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Accepted: 01/10/2024] [Indexed: 02/25/2024] Open
Abstract
BACKGROUND AND PURPOSE This prospective study aimed to investigate adaptive magnetic resonance (MR)-guided stereotactic body radiation therapy (MRgSBRT) with rectal spacer for localized prostate cancer (PC) and report 1-year clinical outcomes. MATERIALS AND METHODS Thirty-four consecutive patients with low- to high-risk localized PC that underwent 5-fraction adaptive MRgSBRT with rectal spacer were enrolled. The dosimetric comparison was performed on a risk- and age-matched cohort treated with MRgSBRT but without a spacer at a similar timepoint. Clinician-reported outcomes were based on Common Terminology Criteria for Adverse Events. Patient-reported outcomes were based on the Expanded Prostate Cancer Index Composite (EPIC) questionnaire at baseline, acute (1-3 months), subacute (4-12 months), and late (> 12 months) phases. RESULTS The median follow-up was 390 days (range 28-823) and the median age was 70 years (range 58-82). One patient experienced rectal bleeding soon after spacer insertion that subsided before MRgSBRT. The median distance between the midline of the prostate midgland and the rectum after spacer insertion measured 7.8 mm (range 2.6-15.3), and the median length of the spacer was 45.9 mm (range 16.8-62.9) based on T2-weighted MR imaging. The use of spacer resulted in significant improvements in target coverage (V100% > 95% = 98.6% [range 93.4-99.8] for spacer vs. 97.8% [range 69.6-99.7] for non-spacer) and rectal sparing (V95% < 3 cc = 0.7 cc [range 0-4.6] for spacer vs. 4.9 cc [range 0-12.5] for non-spacer). Nine patients (26.5%) experienced grade 1 gastrointestinal toxicities, and no grade ≥ 2 toxicities were observed. During the 1-year follow-up period, EPIC scores for the bowel domain remained stable and were the highest among all other domains. CONCLUSIONS MRgSBRT with rectal spacer for localized PC showed exceptional tolerability with minimal gastrointestinal toxicities and satisfactory patient-reported outcomes. Improvements in dosimetry, rectal sparing, and target coverage were achieved with a rectal spacer. Randomized trials are warranted for further validation.
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Affiliation(s)
- Darren M C Poon
- Comprehensive Oncology Centre, 11/F, HKSH Eastern Building, 3 Tung Wong Roade Road, Shau Kei Wan, Hong Kong SAR.
| | - Jing Yuan
- Research Department, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - Oi Lei Wong
- Research Department, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - Bin Yang
- Medical Physics Department, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - Mei Yan Tse
- Medical Physics Department, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - Ka Ki Lau
- Medical Physics Department, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - Sin Ting Chiu
- Department of Radiotherapy, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - Peter Ka-Fung Chiu
- SH Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Chi Fai Ng
- SH Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Ka Lun Chui
- SH Ho Urology Centre, Department of Surgery, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR
| | - Yiu Ming Kwong
- Urology Centre, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - Wai Kit Ma
- Hong Kong Urology Clinic, Hong Kong, Hong Kong SAR
| | - Kin Yin Cheung
- Medical Physics Department, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - George Chiu
- Department of Radiotherapy, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
| | - Siu Ki Yu
- Medical Physics Department, Hong Kong Sanatorium and Hospital, Happy Valley, Hong Kong, Hong Kong SAR
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Harvey M, Ong WL, Chao M, Udovicich C, McBride S, Bolton D, Eastham J, Perera M. Comprehensive review of the use of hydrogel spacers prior to radiation therapy for prostate cancer. BJU Int 2023; 131:280-287. [PMID: 35689413 PMCID: PMC9734283 DOI: 10.1111/bju.15821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES To provide a comprehensive narrative review of the published data on the impact of hydrogel spacers on rectal dosimetry and toxicity and to outline the practicalities of inserting hydrogel spacers. RESULTS A growing body of evidence suggests that the administration of hydrogel spacers is safe and is associated with limited peri-operative morbidity. The impact on rectal dosimetry has been clearly established and use of hydrogel spacers is associated with reduced rectal morbidity. These results have been corroborated by several Phase II and III clinical trials and subsequent meta-analysis. There are several areas for future research, including the role of hydrogel spacers in prostate stereotactic beam radiotherapy and post-radiotherapy local recurrence. CONCLUSIONS Hydrogel spacers provide a low-morbidity method to potential reduce rectal toxicity after radiation therapy in men with prostate cancer. Data outlining sexual function and oncological outcomes are limited to date. Future studies, currently being conducted, may provide further clarification of the role of hydrogel spacers in prostate cancer management.
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Affiliation(s)
- Michael Harvey
- Urology Department, Austin Health, Melbourne, Victoria 3000, Australia
| | - Wee Loon Ong
- Department of Radiation Oncology, Alfred Health, Melbourne, 3004, Australia
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne 3000 Victoria
| | - Michael Chao
- Department of Radiation Oncology, Olivia Newton John Cancer Wellness and Research Centre, Austin Health, Melbourne, Victoria 3000, Australia
- Genesis Cancer Care Victoria, Ringwood East, Victoria 3135, Australia
| | - Cristian Udovicich
- Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Victoria 3010, Australia
| | - Sean McBride
- Radiation Oncology Service, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Damien Bolton
- Urology Department, Austin Health, Melbourne, Victoria 3000, Australia
| | - James Eastham
- Urology Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, USA
| | - Marlon Perera
- Urology Department, Austin Health, Melbourne, Victoria 3000, Australia
- Urology Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, USA
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Forsthoefel M, Hankins R, Ballew E, Frame C, DeBlois D, Pang D, Krishnan P, Unger K, Kowalczyk K, Lynch J, Dritschilo A, Collins SP, Lischalk JW. Prostate Cancer Treatment with Pencil Beam Proton Therapy Using Rectal Spacers sans Endorectal Balloons. Int J Part Ther 2022; 9:28-41. [PMID: 35774493 PMCID: PMC9238133 DOI: 10.14338/ijpt-21-00039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 02/01/2022] [Indexed: 11/21/2022] Open
Abstract
Purpose Proton beam radiotherapy (PBT) has been used for the definitive treatment of localized prostate cancer with low rates of high-grade toxicity and excellent patient-reported quality-of-life metrics. Technological advances such as pencil beam scanning (PBS), Monte Carlo dose calculations, and polyethylene glycol gel rectal spacers have optimized prostate proton therapy. Here, we report the early clinical outcomes of patients treated for localized prostate cancer using modern PBS–PBT with hydrogel rectal spacing and fiducial tracking without the use of endorectal balloons. Materials and Methods This is a single institutional review of consecutive patients treated with histologically confirmed localized prostate cancer. Prior to treatment, all patients underwent placement of fiducials into the prostate and insertion of a hydrogel rectal spacer. Patients were typically given a prescription dose of 7920 cGy at 180 cGy per fraction using a Monte Carlo dose calculation algorithm. Acute and late toxicity were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE), version 5. Biochemical failure was defined using the Phoenix definition. Results From July 2018 to April 2020, 33 patients were treated (median age, 75 years). No severe acute toxicities were observed. The most common acute toxicity was urinary frequency. With a median follow-up of 18 months, there were no high-grade genitourinary late toxicities; however, one grade 3 gastrointestinal toxicity was observed. Late erectile dysfunction was common. One treatment failure was observed at 21 months in a patient treated for high-risk prostate cancer. Conclusion Early clinical outcomes of patients treated with PBS–PBT using Monte Carlo–based planning, fiducial placement, and rectal spacers sans endorectal balloons demonstrate minimal treatment-related toxicity with good oncologic outcomes. Rectal spacer stabilization without the use of endorectal balloons is feasible for the use of PBS–PBT.
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Affiliation(s)
- Matthew Forsthoefel
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - Ryan Hankins
- Department of Urology, Georgetown University Hospital, Washington, DC, USA
| | - Elizabeth Ballew
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - Cara Frame
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - David DeBlois
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - Dalong Pang
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - Pranay Krishnan
- Department of Radiology, Georgetown University Hospital, Washington, DC, USA
| | - Keith Unger
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - Keith Kowalczyk
- Department of Urology, Georgetown University Hospital, Washington, DC, USA
| | - John Lynch
- Department of Urology, Georgetown University Hospital, Washington, DC, USA
| | - Anatoly Dritschilo
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - Sean P. Collins
- Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, USA
| | - Jonathan W. Lischalk
- Department of Radiation Oncology, Perlmutter Cancer Center at New York University Langone Hospital – Long Island, New York, NY, USA
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Lischalk JW, Blacksburg S, Mendez C, Repka M, Sanchez A, Carpenter T, Witten M, Garbus JE, Evans A, Collins SP, Katz A, Haas J. Stereotactic body radiation therapy for the treatment of localized prostate cancer in men with underlying inflammatory bowel disease. Radiat Oncol 2021; 16:126. [PMID: 34243797 PMCID: PMC8267228 DOI: 10.1186/s13014-021-01850-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 06/24/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Historically, IBD has been thought to increase the underlying risk of radiation related toxicity in the treatment of prostate cancer. In the modern era, contemporary radiation planning and delivery may mitigate radiation-related toxicity in this theoretically high-risk cohort. This is the first manuscript to report clinical outcomes for men diagnosed with prostate cancer and underlying IBD curatively treated with stereotactic body radiation therapy (SBRT). METHODS A large institutional database of patients (n = 4245) treated with SBRT for adenocarcinoma of the prostate was interrogated to identify patients who were diagnosed with underlying IBD prior to treatment. All patients were treated with SBRT over five treatment fractions using a robotic radiosurgical platform and fiducial tracking. Baseline IBD characteristics including IBD subtype, pre-SBRT IBD medications, and EPIC bowel questionnaires were reviewed for the IBD cohort. Acute and late toxicity was evaluated using the CTCAE version 5.0. RESULTS A total of 31 patients were identified who had underlying IBD prior to SBRT for the curative treatment of prostate cancer. The majority (n = 18) were diagnosed with ulcerative colitis and were being treated with local steroid suppositories for IBD. No biochemical relapses were observed in the IBD cohort with early follow up. High-grade acute and late toxicities were rare (n = 1, grade 3 proctitis) with a median time to any GI toxicity of 22 months. Hemorrhoidal flare was the most common low-grade toxicity observed (n = 3). CONCLUSION To date, this is one of the largest groups of patients with IBD treated safely and effectively with radiation for prostate cancer and the only review of patients treated with SBRT. Caution is warranted when delivering therapeutic radiation to patients with IBD, however modern radiation techniques appear to have mitigated the risk of GI side effects.
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Affiliation(s)
- Jonathan W Lischalk
- Department of Radiation Oncology, NYCyberKnife at Perlmutter Cancer Center - Manhattan, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave, New York, NY, 11501, USA.
| | - Seth Blacksburg
- Department of Radiation Medicine, Lenox Hill Hospital - Northwell Health, New York, NY, 10075, USA
| | - Christopher Mendez
- Department of Radiation Oncology, NYCyberKnife at Perlmutter Cancer Center - Manhattan, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave, New York, NY, 11501, USA
| | - Michael Repka
- Department of Radiation Oncology, NYCyberKnife at Perlmutter Cancer Center - Manhattan, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave, New York, NY, 11501, USA
| | - Astrid Sanchez
- Department of Radiation Oncology, NYCyberKnife at Perlmutter Cancer Center - Manhattan, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave, New York, NY, 11501, USA
| | - Todd Carpenter
- Department of Radiation Oncology, NYCyberKnife at Perlmutter Cancer Center - Manhattan, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave, New York, NY, 11501, USA
| | - Matthew Witten
- Department of Radiation Oncology, NYCyberKnife at Perlmutter Cancer Center - Manhattan, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave, New York, NY, 11501, USA
| | - Jules E Garbus
- Department of Surgery, New York University Long Island School of Medicine, Mineola, NY, 11501, USA
| | - Andrew Evans
- Department of Radiation Oncology, New York University School of Medicine, New York, NY, USA
| | - Sean P Collins
- Department of Radiation Medicine, Medstar Georgetown University Hospital, Washington, DC, 20007, USA
| | - Aaron Katz
- Department of Urology, New York University Long Island School of Medicine, Mineola, NY, 11501, USA
| | - Jonathan Haas
- Department of Radiation Oncology, NYCyberKnife at Perlmutter Cancer Center - Manhattan, Perlmutter Cancer Center at New York University Langone Hospital - Long Island, 150 Amsterdam Ave, New York, NY, 11501, USA
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Meyer AR, Dharmaraj D, Harb R, Pavlovich CP, Allaf ME, Gorin MA. Perirectal hydrogel spacer placement prior to prostate radiation therapy using a probe-mounted needle guide. Clin Transl Radiat Oncol 2021; 29:102-105. [PMID: 34195392 PMCID: PMC8234349 DOI: 10.1016/j.ctro.2021.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 05/03/2021] [Accepted: 05/09/2021] [Indexed: 11/14/2022] Open
Abstract
Perirectal spacer placement minimizes the risk of bowel toxicity from prostate radiation therapy. We show that a novel probe-mounted needle guide can be safely used for perirectal spacer insertion. The main advantage of this device is that it ensures needle visualization throughout the procedure.
In this report we describe our successful adoption of a single-use, probe-mounted, needle guide for perirectal hydrogel spacer placement prior to radiation therapy for prostate cancer. Use of this device eliminates the need for a mechanical stepper unit and facilitates perirectal hydrogel placement by ensuring alignment of the injection needle with the ultrasound probe.
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Affiliation(s)
- Alexa R Meyer
- The James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins, University School of Medicine, Baltimore, MD, USA
| | - Divya Dharmaraj
- The James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins, University School of Medicine, Baltimore, MD, USA
| | - Rana Harb
- The James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins, University School of Medicine, Baltimore, MD, USA
| | - Christian P Pavlovich
- The James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins, University School of Medicine, Baltimore, MD, USA
| | - Mohamad E Allaf
- The James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins, University School of Medicine, Baltimore, MD, USA
| | - Michael A Gorin
- Urology Associates and UPMC Western Maryland, Cumberland, MD, USA.,Deparmtnet of Urology, University of Pittsburg School of Medicine, Pittsburg, PA, USA
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Lafond C, Barateau A, N'Guessan J, Perichon N, Delaby N, Simon A, Haigron P, Mylona E, Acosta O, de Crevoisier R. Planning With Patient-Specific Rectal Sub-Region Constraints Decreases Probability of Toxicity in Prostate Cancer Radiotherapy. Front Oncol 2020; 10:1597. [PMID: 33042802 PMCID: PMC7517942 DOI: 10.3389/fonc.2020.01597] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 07/23/2020] [Indexed: 11/27/2022] Open
Abstract
Background: A rectal sub-region (SRR) has been previously identified by voxel-wise analysis in the inferior-anterior part of the rectum as highly predictive of rectal bleeding (RB) in prostate cancer radiotherapy. Translating the SRR to patient-specific radiotherapy planning is challenging as new constraints have to be defined. A recent geometry-based model proposed to optimize the planning by determining the achievable mean doses (AMDs) to the organs at risk (OARs), taking into account the overlap between the planning target volume (PTV) and OAR. The aim of this study was to quantify the SRR dose sparing by using the AMD model in the planning, while preserving the dose to the prostate. Material and Methods: Three-dimensional volumetric modulated arc therapy (VMAT) planning dose distributions for 60 patients were computed following four different strategies, delivering 78 Gy to the prostate, while meeting the genitourinary group dose constraints to the OAR: (i) a standard plan corresponding to the standard practice for rectum sparing (STDpl), (ii) a plan adding constraints to SRR (SRRpl), (iii) a plan using the AMD model applied to the rectum only (AMD_RECTpl), and (iv) a final plan using the AMD model applied to both the rectum and the SRR (AMD_RECT_SRRpl). After PTV dose normalization, plans were compared with regard to dose distributions, quality, and estimated risk of RB using a normal tissue complication probability model. Results: AMD_RECT_SRRpl showed the largest SRR dose sparing, with significant mean dose reductions of 7.7, 3, and 2.3 Gy, with respect to the STDpl, SRRpl, and AMD_RECTpl, respectively. AMD_RECT_SRRpl also decreased the mean rectal dose by 3.6 Gy relative to STDpl and by 3.3 Gy relative to SRRpl. The absolute risk of grade ≥1 RB decreased from 22.8% using STDpl planning to 17.6% using AMD_RECT_SRRpl considering SRR volume. AMD_RECT_SRRpl plans, however, showed slightly less dose homogeneity and significant increase of the number of monitor units, compared to the three other strategies. Conclusion: Compared to a standard prostate planning, applying dose constraints to a patient-specific SRR by using the achievable mean dose model decreased the mean dose by 7.7 Gy to the SRR and may decrease the relative risk of RB by 22%.
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Affiliation(s)
- Caroline Lafond
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
| | - Anaïs Barateau
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
| | - Joël N'Guessan
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
| | - Nicolas Perichon
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
| | - Nolwenn Delaby
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
| | - Antoine Simon
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
| | - Pascal Haigron
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
| | - Eugenia Mylona
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
| | - Oscar Acosta
- Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI - UMR 1099, Rennes, France
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Proposed Hydrogel-Implant Quality Score and a Matched-Pair Study for Prostate Radiation Therapy. Pract Radiat Oncol 2020; 10:202-208. [PMID: 32088428 DOI: 10.1016/j.prro.2020.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/27/2020] [Accepted: 02/12/2020] [Indexed: 12/19/2022]
Abstract
PURPOSE SpaceOAR hydrogel has been Food and Drug Administration approved to reduce rectal toxicity in prostate radiation therapy. Training and certification for this procedure is performed by the manufacturer, without independent quality measures. We propose a Hydrogel-Implant Quality Score (HIQS) as a surrogate to quantify hydrogel placement accuracy, to assist clinicians in tracking their implant proficiency, and to support quality improvement. A matched-pair study was designed to investigate the benefit of SpaceOAR in rectal dose reduction for low-dose-rate brachytherapy and to validate the principle of the proposed HIQS. METHODS Eighty-one prostate patients were retrospectively selected for this study. Each patient had SpaceOAR implantation under manufacturer supervision. Postprocedure computed tomography and T2-weighted magnetic resonance imaging were acquired for radiation planning. A HIQS system was proposed to evaluate the hydrogel placement quality. Hydrogel implantation was performed immediately after LDR seed placement. For each LDR patient, a non-SpaceOAR patient was matched based upon intraoperative rectal dose and prostate coverage. Intraoperative and postoperative rectal dose reduction was compared between SpaceOAR and non-SpaceOAR groups. RESULTS The average HIQS was 77 ± 10.8 (range, 49-97). Rectal anatomic distortions were seen in 17 cases. Significant rectal dose reductions between intraoperative and postoperative plans were found for SpaceOAR patients compared with non-SpaceOAR patients (25.1 Gy vs -5.0 Gy for ΔD2cc and 65.7 Gy vs 13.0 for ΔD0.1cc). Additional rectal dose reductions (8.4 Gy for ΔD2cc and 12.7 Gy for ΔD0.1cc) were found for patients without rectal distortion when SpaceOAR was used. CONCLUSIONS The proposed HIQS system measured the hydrogel placement quality and provided insights into clinician learning and DVH outcome. SpaceOAR was shown to be effective in reducing rectal dose for LDR patients.
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