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Hwang ME, Mayeda M, Shaish H, Elliston CD, Spina CS, Wenske S, Deutsch I. Dosimetric feasibility of neurovascular bundle-sparing stereotactic body radiotherapy with periprostatic hydrogel spacer for localized prostate cancer to preserve erectile function. Br J Radiol 2021; 94:20200433. [PMID: 33586999 PMCID: PMC8011244 DOI: 10.1259/bjr.20200433] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Objective: We aim to test the hypothesis that neurovascular bundle (NVB) displacement by rectal hydrogel spacer combined with NVB delineation as an organ at risk (OAR) is a feasible method for NVB-sparing stereotactic body radiotherapy. Methods: Thirty-five men with low- and intermediate-risk prostate cancer who underwent rectal hydrogel spacer placement and pre-, post-spacer prostate MRI studies were treated with prostate SBRT (36.25 Gy in five fractions). A prostate radiologist contoured the NVB on both the pre- and post-spacer T2W MRI sequences that were then registered to the CT simulation scan for NVB-sparing radiation treatment planning. Three SBRT treatment plans were developed for each patient: (1) no NVB sparing, (2) NVB-sparing using pre-spacer MRI, and (3) NVB-sparing using post-spacer MRI. NVB dose constraints include maximum dose 36.25 Gy (100%), V34.4 Gy (95% of dose) <60%, V32Gy <70%, V28Gy <90%. Results: Rectal hydrogel spacer placement shifted NVB contours an average of 3.1 ± 3.4 mm away from the prostate, resulting in a 10% decrease in NVB V34.4 Gy in non-NVB-sparing plans (p < 0.01). NVB-sparing treatment planning reduced the NVB V34.4 by 16% without the spacer (p < 0.01) and 25% with spacer (p < 0.001). NVB-sparing did not compromise PTV coverage and OAR endpoints. Conclusions: NVB-sparing SBRT with rectal hydrogel spacer significantly reduces the volume of NVB treated with high-dose radiation. Rectal spacer contributes to this effect through a dosimetrically meaningful displacement of the NVB that may significantly reduce RiED. These results suggest that NVB-sparing SBRT warrants further clinical evaluation. Advances in knowledge: This is a feasibility study showing that the periprostatic NVBs can be spared high doses of radiation during prostate SBRT using a hydrogel spacer and nerve-sparing treatment planning.
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Affiliation(s)
- Mark E Hwang
- Department of Radiation Oncology, University of Wisconsin Health Cancer Center at ProHealth Care, Waukesha, WI, USA
| | - Mark Mayeda
- Department of Radiation Oncology, Columbia University Medical Center, New York, NY, USA
| | - Hiram Shaish
- Department of Radiology, Columbia University Medical Center, New York, NY, USA
| | - Carl D Elliston
- Department of Radiation Oncology, Columbia University Medical Center, New York, NY, USA
| | - Catherine S Spina
- Department of Radiation Oncology, Columbia University Medical Center, New York, NY, USA
| | - Sven Wenske
- Department of Urology, Columbia University Medical Center, New York, NY, USA
| | - Israel Deutsch
- Department of Radiation Oncology, Columbia University Medical Center, New York, NY, USA
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King RB, Osman SO, Fairmichael C, Irvine DM, Lyons CA, Ravi A, O'Sullivan JM, Hounsell AR, Mitchell DM, McGarry CK, Jain S. Efficacy of a rectal spacer with prostate SABR-first UK experience. Br J Radiol 2018; 91:20170672. [PMID: 29182384 DOI: 10.1259/bjr.20170672] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
OBJECTIVE This study assessed the use of implanted hydrogel rectal spacers for stereotactic ablative radiotherapy-volumetric modulated arc therapy (SABR-VMAT) patients, investigating practicality, dosimetric impact, normal tissue complication probability (NTCP) and early toxicity. METHODS Data from the first 6 patients treated within a prostate SABR and rectal spacer trial were examined to determine spacer insertion tolerability, resultant changes in treatment planning and dosimetry and early toxicity effects. CT scans acquired prior to spacer insertion were used to generate SABR plans which were compared to post-insertion plans. Plans were evaluated for target coverage, conformity, and organs at risk doses with NTCPs also determined from resultant dose fluences. Early toxicity data were also collected. RESULTS All patients had successful spacer insertion under local anaesthetic with maximal Grade 1 toxicity. All plans were highly conformal, with no significant differences in clinical target volume dose coverage between pre- and post-spacer plans. Substantial improvements in rectal dose metrics were observed in post-spacer plans, e.g. rectal volume receiving 36 Gy reduced by ≥42% for all patients. Median NTCP for Grade 2 + rectal bleeding significantly decreased from 4.9 to 0.8% with the use of a rectal spacer (p = 0.031). To date, two episodes of acute Grade 1 proctitis have been reported following treatment. CONCLUSION The spacer resulted in clinically and statistically significant reduction in rectal doses for all patients. Advances in knowledge: This is one of the first studies to investigate the efficacy of a hydrogel spacer in prostate SABR treatments. Observed dose sparing of the rectum is predicted to result in meaningful clinical benefit.
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Affiliation(s)
- Raymond B King
- 1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.,2 Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
| | - Sarah Os Osman
- 1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.,2 Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
| | - Ciaran Fairmichael
- 1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.,3 Department of Clinical Oncology, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
| | - Denise M Irvine
- 2 Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
| | - Ciara A Lyons
- 1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.,3 Department of Clinical Oncology, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland.,4 Department of Clinical Oncology, North West Cancer Centre, Altnagelvin Area Hospital , Londonderry , Northern Ireland
| | - Ananth Ravi
- 5 Department of Medical Physics, Odette Cancer Centre, Sunnybrook Health Sciences Centre , Toronto , Canada
| | - Joe M O'Sullivan
- 1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.,3 Department of Clinical Oncology, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
| | - Alan R Hounsell
- 1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.,2 Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
| | - Darren M Mitchell
- 3 Department of Clinical Oncology, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
| | - Conor K McGarry
- 1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.,2 Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
| | - Suneil Jain
- 1 Centre for Cancer Research and Cell Biology, Queen's University Belfast , Belfast , Ireland.,3 Department of Clinical Oncology, Northern Ireland Cancer Centre, Belfast City Hospital , Belfast , Ireland
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