Illustration of SpaceOAR Hydrogel

Clinical Summary

Expanding the Utilization of Rectal Spacer Hydrogel for Larger Prostate Glands (>80cc): Feasibility and Dosimetric Outcomes

By: Fagundes M, Rodrigues MA, Olszewski S, et al. 

33 patients with localized prostate cancer with glands exceeding 80cc were treated at a single institution using intensity-modulated radiotherapy (IMRT, n=15) and proton therapy (n=18) from 2017 to 2019. 16 patients received conventional fractionation and 17 received hypofractionation. Previous prospective multi-institutional studies only included prostates <80cc.1 The mean separation was 9.9 mm (range, 6.6 - 19.4 mm) for glands measuring >80 to 100 cm3 and 8.8 mm (range, 4.7 - 12.3 mm) for glands >100 cm3 . Patients were assessed weekly using common terminology criteria for adverse events (CTCAE).

Dosimetric outcomes

Conventional fractionation (78 Gy/39 fractions)
  Pts rV75 rV70 rV60 rV50
All 16 0.84% (0-2.7) 2.25% (0-4.7) 5.61% (1.7-9.5) 10.5% (2.39-15.2)
P + SV 4 0.75% (0.06-1.77) 2% (0.75-4.4) 5.47% (2.5-9.5) 10.1% (6.4-15.2)
P + SV + Lns 12 0.87% (0-2.7%) 2.3% (0-4.7) 5.66% (1.7-8.9) 10.7% (2.3-14.9)
P + SV (IMRT) 2  0.58% (0.06-1.1) 1.61% (0.93-2.3) 4.95% (4.5-5.4) 9.45% (9.4-9.5)
P + SV (PT) 2 0.93% (0.09-1.77) 2.57% (0.75-4.4) 6% (2.5-9.5) 10.8% (6.4-15.2)
Moderate hypofractionation (70 Gy/28 fractions)
  Pts rV65 rV63 rV60 rV50
All P + SV 17 1.67% (0-5.8) 2.3% (0.1-6.7) 3.4% (0.4-9.6) 8.6% (3.3-15.7)
P + SV (IMRT) 9 1.16% (0-4.6) 1.65% (0.1-5.8) 2.5% (0.3-7.8) 6.9% (2.46-15)
P + SV (PT) 8 2.24% (0.7-5.8) 3.1% (1.3-6.7) 4.48% (2.4-9.6) 10.5% (4.9-15.7)
Abbreviations: IMRT = intensity modulated radiation therapy; (P + SV) = prostate plus seminal vesicles;
(P + SV + Lns) = prostate plus seminal vesicles plus lymph nodes; PT = proton therapy; Pts = patients.
“Hydrogel placement is feasible in large glands >80cc, even when including a subgroup of patients with prostates >100cc (100.1-186.6 cc) with very favorable dosimetric outcomes which are in line with benchmark published results with smaller glands.”

Link to full article >

Limitations of this report include:
  • Study was retrospective in nature
  • The SpaceOAR Hydrogel pivotal study did not evaluate glands >80cc so the results may not be comparable
  • This study was not designed or powered to make definitive claims about the benefits of a spacer
  • These results may not be achieved with other large gland protocols
  • The pivotal study done for SpaceOAR Hydrogel utilized fractionation schedules of 79.2Gy over 44 fractions

Frequently Asked Questions

We've got the answers.


Get SpaceOAR Hydrogel

Become a certified applier.


Sign Up

Get exclusive updates and clincial data.


  1. 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. Int J Radiat Oncol Biol Phys. 2015;92(5):971-977.

78Gy over 39 fractions was not the method used in the SpaceOAR™ Hydrogel single-blind Phase III trial performed to evaluate dosimetric and clinical effects of SpaceOAR Hydrogel. IG-IMRT delivered at 79.2 Gy in 1.8-Gy fractions was the method used.

Results from case studies are not necessarily predictive of results in other cases. Results in other cases may vary.

The content of this article/publication is under the sole responsibility of its author/publisher and does not represent the opinion of BSC.

Caution: U.S. Federal law restricts this device to sale by or on the order of a physician.

CAUTION: The law restricts these devices to sale by or on the order of a physician. Indications, contraindications, warnings and instructions for use can be found in the product labeling supplied with each device. Information for use only in countries with applicable health authority registrations. This material not intended for use in France.

Products shown for INFORMATION purposes only and may not be approved or for sale in certain countries. Please check availability with your local sales representative or customer service.

All images are the property of Boston Scientific. All trademarks are the property of their respective owners.