Jesse Conterato BAampSc October 24 2016 Hydrogel Spacers MRI Comparison Axial View Sagittal View Pinkawa et al WJCO 2015 Without Spacer With Spacer Hydrogel Spacer Moves the Rectum Outside of High Dose Volumes CT Comparison ID: 932444
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Slide1
Reduction in Rectal Dose in Prostate Cancer Patients Using Hydrogel Spacer During Proton Therapy
Jesse Conterato,
BA&Sc
October 24, 2016
Slide2Hydrogel Spacers: MRI Comparison
Axial View
Sagittal View
Pinkawa
et al. WJCO 2015
Without Spacer
With Spacer
Slide3Hydrogel Spacer Moves the Rectum Outside of High Dose Volumes: CT Comparison
3
Rectal Balloon
Hydrogel Spacer
Prostate
Rectum
Eval
Hydrogel Spacer
Axial View
Sagittal View
Rectal Balloon
Slide4Can hydrogel spacers reduce rectal dose in patients undergoing proton therapy?
Prospective trials demonstrated significant rectal dose reduction in patients undergoing IMRT for prostate cancer
Few studies have examined the use of hydrogel spacers in patients treated with proton therapy
Also expect to see rectal dose reduction in the setting of proton therapy
4
Slide5Purpose
To compare the reduction of rectal dose using hydrogel spacer (HS) versus daily
endo
-rectal balloon (RB) in men receiving definitive proton beam radiotherapy (PBRT) for prostate cancer
Slide6Retrospective review of prostate cancer patients undergoing definitive PBRT at a single institution
Prospective Proton Collaborative Group Registry
Others reviewed in accordance with our institutional ATOM protocol and HIPAA
63 consecutive patients with hydrogel spacer in place
Treatment era: April 2015 – February 2016
Matched by NCCN risk stratification to patient cohort (N=65) that used daily rectal balloonTreatment era: January – December 2014
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Slide7Methods
Inclusion criteria:
Completed treatment of 79.2 Cobalt Gray Equivalent (CGE) in 44 fractions
Rectum, bladder, and penile bulb
dosimetric data retrospectively assessed7
Slide8Pencil Beam Scanning Vs. Uniform Scanning
8
Cohorts, overall and within each target group, had similar numbers of patients treated with PBS and Uniform Scanning
Slide9Patient Characteristics
9
Slide10HS patients, averaged across all PBRT targets, experienced a significant reduction in both Rectum Eval
V50 and V70
10
Rectal Dose Outcomes: Rectum
Eval V50 and V70
Slide11Rectal Dose Outcomes: PBS vs. Uniform Scanning
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Hydrogel spacer cohort experienced significant reduction in average Rectum
Eval
V70 compared to the rectal balloon cohort, regardless of delivery method
p<0.0005
p<0.0005
Slide12Rectal Dose Outcomes: PBRT Targets
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p = 0.0003
p = 0.002
p = 0.3
p < 0.0005
p < 0.0005
p < 0.0005
Slide13Conclusion
The use of hydrogel spacers during definitive PBRT for prostate cancer resulted in lower rectal doses compared to the use daily
endo
-rectal balloonsAdditional follow-up is needed to assess rectal toxicity
Slide14Acknowledgements
Lisa McGee, MD
William
Hartsell
, MDShae Gans, CMD
Vinai Gondi, MDJohn Chang, MDMegan Dunn, PhD, MSHS
Steve Laub, MPMark Punkuch
, PhDChicago Proton Center StaffProton Collaborative Group 14