1. Jesse Conterato, BA&Sc. RSNA 2016
Assessment of Acute Toxicity in Prostate Cancer Patients using Hydrogel Spacer During Proton Therapy
Jesse Conterato, BA&Sc.
RSNA 2016

2. Hydrogel Spacers: MRI Comparison
Absorbable polyethylene glycol hydrogel spacers are injected into the peri-rectal space.
Moves the anterior rectal wall outside of high dose volumes
Without Spacer
With Spacer
Axial
View
Rectum
Hydrogel Spacer
Sagittal
View
Prostate
Pinkawa et al. WJCO 2015

3. Hydrogel Spacers During Proton Therapy?
Prospective IMRT trials demonstrate advantage of hydrogel spacer during treatment for prostate cancer:
Rectal dose reduction
Severity of rectal toxicity reduced
(Song et al. 2013, Mariados et al. 2015, Uhl et al. 2014)
Mariados et al. Int J Radiation Oncol Biol Phys 2015
Few studies have examined the use of hydrogel spacers in patients treated with proton therapy

4. Purpose
To evaluate the acute toxicity outcomes in prostate cancer patients treated with definitive proton beam radiotherapy (PBRT) with a hydrogel spacer (HS) in place

5. Methods
Retrospective review of prostate cancer patients undergoing definitive PBRT at a single institution
Patient data collected from:
Prospective Proton Collaborative Group Registry
Our institutional Advancements Through Outcomes Measures protocol
63 consecutive patients with hydrogel spacer in place
Treatment era: April 2015 – February 2016
All patients completed treatment of 79.2 Cobalt Gray Equivalent (CGE) in 44 fractions
Acute Toxicity was defined as occurring during the PBRT treatment period

6. Methods and Patient Characteristics
Toxicity was prospectively assessed weekly during PBRT and scored according to CTCAE v4.0 in 6 genitourinary (GU) and 4 gastrointestinal (GI) categories:
GU: Urinary Tract Pain, Urinary Frequency, Urinary Retention, Urinary Incontinence, Urinary Urgency, Hematuria
GI: Fecal Incontinence, Rectal Hemorrhage, Proctitis, and Diarrhea.

7. Methods and Patient Characteristics

8. Results: Spacer Placement Safety
No infections were observed after hydrogel injection, performed under trans-rectal ultrasound guidance
Prostate
Prostate
Prostate
Prostate
Müller et al. Radiol Oncol 2016

9. Results: Overall GU Toxicity
Most common forms of Grade 2 GU toxicity:
Urinary frequency, retention, and urgency
Grade 3 GU toxicity:
During PBRT, one patient experienced GR3 urinary tract pain while being treated for UTI
One patient, with prostate volume of mL, underwent Green Light procedure for urinary retention prior to starting PBRT

10. Results: Overall GI Toxicity
Grade 2 Toxicities:
One patient experienced GR2 Fecal Incontinence during PBRT
One patient with pre-existing hemorrhoids experienced GR2 Rectal Hemorrhage and was treated with Proctocream

11. Results: GU Toxicity by Proton Target
Change in GU Toxicity Score
No Increase
1 GR Increase
2 GR Increase
Prostate Only 7%
79%
14%
Prostate and Seminal Vesicles
19%
58%
22%
Prostate, Seminal Vesicles and Pelvic Nodes
31%
62% 8%

12. Results: GI Toxicity by Proton Target
Change in GI Toxicity Score
No Increase
1 GR Increase
2 GR Increase
Prostate Only
71%
21% 7%
Prostate and Seminal Vesicles
78%
22% 0%
Prostate, Seminal Vesicles and Pelvic Nodes
62%
38%

13. Conclusion
The use of hydrogel spacers during definitive PBRT for prostate cancer resulted in acceptably low rates of acute GU and GI toxicity
Additional follow-up is needed to assess effects of hydrogel spacer placement on late rectal toxicity

14. Acknowledgements Lisa McGee, MD William Hartsell, MD
Dean Conterato, MD
Vinai Gondi, MD
John Chang, MD
Shae Gans, CMD
Megan Dunn, PhD, MSHS
Steven Laub, MMP
Chicago Proton Center Staff
Proton Collaborative Group

15. Works Cited
Deville C, Both S, Bui V et al. Acute gastrointestinal and genitourinary toxicity of image-guided intensity modulated radiation therapy for prostate cancer using a daily water-filled endorectal balloon. Radiation Oncology 2012; 7: 1.
Pinkawa M. Current role of spacers for prostate cancer radiotherapy. World journal of clinical oncology 2015; 6: 189.
Song DY, Herfarth KK, Uhl M et al. A multi-institutional clinical trial of rectal dose reduction via injected polyethylene-glycol hydrogel during intensity modulated radiation therapy for prostate cancer: analysis of dosimetric outcomes. International Journal of Radiation Oncology* Biology* Physics 2013; 87:
Mariados N, Sylvester J, Shah D et al. Hydrogel spacer prospective multicenter randomized controlled pivotal trial: dosimetric and clinical effects of perirectal spacer application in men undergoing prostate image guided intensity modulated radiation therapy. International Journal of Radiation Oncology* Biology* Physics 2015; 92:
Uhl M, Herfarth K, Eble MJ et al. Absorbable hydrogel spacer use in men undergoing prostate cancer radiotherapy: 12 month toxicity and proctoscopy results of a prospective multicenter phase II trial. Radiation Oncology 2014; 9: 1.
Müller A-C, Mischinger J, Klotz T et al. Interdisciplinary consensus statement on indication and application of a hydrogel spacer for prostate radiotherapy based on experience in more than 250 patients. Radiology and Oncology 2016.