Efficacy of a rectal spacer with prostate SABR - first UK experience

Raymond B King, Sarah Os Osman, Ciaran Fairmichael, Denise M Irvine, Ciara A Lyons, Ananth Ravi, Joe M O'Sullivan, Alan R Hounsell, Darren M Mitchell, Conor K McGarry, Suneil Jain

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Abstract

OBJECTIVE: This study assessed the use of implanted hydrogel rectal spacers for 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 CT plans. Plans were evaluated for target coverage, conformity, and organs at risk doses with NTCPs also determined from resultant dose fluences. Early toxicity data was 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 CTV 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 36Gy 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, 2 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.

Original languageEnglish
Pages (from-to)1-32
JournalBritish Journal of Radiology
Early online date28 Nov 2017
DOIs
Publication statusEarly online date - 28 Nov 2017

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Prostate
Hydrogel
Proctitis
Organs at Risk
Local Anesthetics
Rectum
Therapeutics
Hemorrhage

Keywords

  • Journal Article

Cite this

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title = "Efficacy of a rectal spacer with prostate SABR - first UK experience",
abstract = "OBJECTIVE: This study assessed the use of implanted hydrogel rectal spacers for 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 CT plans. Plans were evaluated for target coverage, conformity, and organs at risk doses with NTCPs also determined from resultant dose fluences. Early toxicity data was 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 CTV 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 36Gy 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, 2 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.",
keywords = "Journal Article",
author = "King, {Raymond B} and Osman, {Sarah Os} and Ciaran Fairmichael and Irvine, {Denise M} and Lyons, {Ciara A} and Ananth Ravi and O'Sullivan, {Joe M} and Hounsell, {Alan R} and Mitchell, {Darren M} and McGarry, {Conor K} and Suneil Jain",
year = "2017",
month = "11",
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language = "English",
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Efficacy of a rectal spacer with prostate SABR - first UK experience. / King, Raymond B; Osman, Sarah Os; Fairmichael, Ciaran; Irvine, Denise M; Lyons, Ciara A; Ravi, Ananth; O'Sullivan, Joe M; Hounsell, Alan R; Mitchell, Darren M; McGarry, Conor K; Jain, Suneil.

In: British Journal of Radiology, 28.11.2017, p. 1-32.

Research output: Contribution to journalArticle

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T1 - Efficacy of a rectal spacer with prostate SABR - first UK experience

AU - King, Raymond B

AU - Osman, Sarah Os

AU - Fairmichael, Ciaran

AU - Irvine, Denise M

AU - Lyons, Ciara A

AU - Ravi, Ananth

AU - O'Sullivan, Joe M

AU - Hounsell, Alan R

AU - Mitchell, Darren M

AU - McGarry, Conor K

AU - Jain, Suneil

PY - 2017/11/28

Y1 - 2017/11/28

N2 - OBJECTIVE: This study assessed the use of implanted hydrogel rectal spacers for 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 CT plans. Plans were evaluated for target coverage, conformity, and organs at risk doses with NTCPs also determined from resultant dose fluences. Early toxicity data was 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 CTV 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 36Gy 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, 2 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.

AB - OBJECTIVE: This study assessed the use of implanted hydrogel rectal spacers for 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 CT plans. Plans were evaluated for target coverage, conformity, and organs at risk doses with NTCPs also determined from resultant dose fluences. Early toxicity data was 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 CTV 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 36Gy 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, 2 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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