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Clinical summary

US Pivotal Trial and Subsequent Analyses

A prospective, multicenter, randomized controlled pivotal trial was performed to assess outcomes following SpaceOAR™ Hydrogel implantation. Spacer safety and effectiveness in consistent perirectal space creation and reduction of rectal irradiation was demonstrated.1

Study design¹


  • T1 or T2
  • Gleason Score ≤ 7
  • PSA ≤ to 20ng/mL
  • < 50% positive cores


  • Prospective
  • Randomized parallel arm
  • Single-blind
  • Multicenter
  • Controlled


  • 20 U.S. Sites


  • 222 patients
  • Randomized 2:1 (Spacer: control)

Procedure design

  • Anesthesia
    • General (36.4%)
    • Local (31.4%)
    • MAC (26%)
  • Prophylactic antibiotics
    • 95% of patients
  • Fiducial/Spacer implant
    • Transperineal

Study flow¹

Study flow illustration. Randomization, a split of SpaceOAR and Control patients. Dosing and follow up.

Initial procedure results

Patients had approximately 13 millimeters of space after SpaceOAR Hydrogel placement. Hydrogel absorption was evident during the 3-month imaging.1

Post implant
(mean space)
 Week prior to 3-month date
(mean space)
 Week after 3-month date
(mean space)
12.6 ± 3.9 mm 10.9 ± 5.8 mm6.8 ± 5.4 mm

Placement success

  • 99% (gel present)


  • 99% of appliers rated the procedure easy or very easy

Safety results

  • No device-related adverse events
  • No delays to onset of IMRT
  • No implant infections
  • No rectal infections or complications
  • 10% with mild transient procedure events

3-year follow-up analysis — Bowel

When compared to the control arm, those with SpaceOAR Hydrogel had a statistically significant smaller volume of rectum treated to all volumes from V50 to V80.2

3 year follow up analysis – bowel bar chart.

When compared to the control arm, there was a significant reduction in late rectal toxicity severity in the SpaceOAR Hydrogel group.2

Grade 2+ Rectal Toxicity bar chart.

3-year follow-up analysis — Urinary

A reduction was seen in cumulative Grade 1+ Urinary Incontinence at 3 years.2

Significant reduction in percent of men with meaningful urinary quality of life declines.2

Urinary incontinence

Grade 1+ urinary incontinence*

Control 15% vs SpaceOAR Hydrogel 4%; P=.046 bar chart.

(Control 15% vs SpaceOAR Hydrogel 4%; P=.046)

Urinary quality of life

Patients with urinary QOL declines

1X MID: Control 30% vs SpaceOAR Hydrogel 17%, P<.05, 2X MID: Control 23% vs SpaceOAR Hydrogel 8%, P<.03 bar chart.

1X MID: (Control 30% vs SpaceOAR Hydrogel 17%, P<.05)
2X MID: (Control 23% vs SpaceOAR Hydrogel 8%, P<.03)

*Grade 1 urinary incontinence: Occasional (e.g., with coughing, sneezing, etc.), pads not indicated (CTCAE Version 4.0)

3-year follow-up analysis — Sexual quality of life

At 3 years, more men potent at baseline and treated with SpaceOAR Hydrogel had erections sufficient for intercourse.3

Patients receiving SpaceOAR Hydrogel reported significantly favorable outcomes relating to erection ability, orgasm ability, erection quality and erection frequency.3

The use of SpaceOAR Hydrogel decreased dose to the penile bulb (11 vs 21 Gy, P <.05), which was associated with improved erectile function compared with the control group based on patient-reported sexual QOL.

Men with erections sufficient for intercourse at 3 years*

Control Group: 37.5% vs SpaceOAR Hydrogel 66.7%, P=.046 bar chart.

(Control: 37.5% vs SpaceOAR Hydrogel 66.7%, P=.046)
*Subpopulation analysis of men with erections sufficient for intercourse at baseline

Men with 1X MID decline in sexual quality of life at 3 years**

Control 75% vs SpaceOAR Hydrogel 53%, P=.064 bar chart.

(Control 75% vs SpaceOAR Hydrogel 53%, P=.064)
**Subpopulation analysis of men who had EPIC score above 60 at baseline

3-year follow-up analysis — Patient quality of life

Control patients experienced a decline in bowel, urinary and sexual quality of life more than SpaceOAR Hydrogel patients.2

Overall benefits/patient wellness

Men with 1X and 2X MID declines in all 3 domains (bowel, urinary and sexual), at 3 years

1X MID Control 20% vs SpaceOAR Hydrogel 2.5%. 2x MID Control 12.5% vs SpaceOAR Hydrogel 0% bar chart.

1X MID (Control 20% vs SpaceOAR Hydrogel 2.5%)
2X MID (Control 12.5% vs SpaceOAR Hydrogel 0%)

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  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 Aug 1;92(5):971–7.
  2. Hamstra DA, Mariados N, Sylvester J, et al. Continued benefit to rectal separation for prostate radiation therapy: final results of a phase III trial. Int J Radiat Oncol Biol Phys. 2017 Apr;97(5):976–85.
  3. Hamstra DA, Mariados N, Sylvester J, et al. Sexual quality of life following prostate intensity modulated radiation therapy (IMRT) with a rectal/prostate spacer: Secondary analysis of a phase 3 trial. Pract Radiat Oncol. 2018;8(1):e7–e15. 

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 labelling supplied with each device or at Products shown for INFORMATION purposes only and may not be approved or for sale in certain countries. This material not intended for use in France.

SpaceOAR and SpaceOAR Vue Hydrogels are intended to temporarily position the anterior rectal wall away from the prostate during radiotherapy for prostate cancer and in creating this space it is the intent of SpaceOAR and SpaceOAR Vue Hydrogels to reduce the radiation dose delivered to the anterior rectum.

SpaceOAR and SpaceOAR Vue Hydrogels contain polyethylene glycol (PEG). SpaceOAR Vue Hydrogel contains iodine.

Prior to using these devices, please review the Instructions for Use for a complete listing of indications, contraindications, warnings, precautions and potential adverse events.

As with any medical treatment, there are some risks involved with the use of SpaceOAR and SpaceOAR Vue Hydrogels. Potential complications associated with SpaceOAR and SpaceOAR Vue Hydrogels include, but are not limited to: pain associated with SpaceOAR and SpaceOAR Vue Hydrogels injection, pain or discomfort associated with SpaceOAR and SpaceOAR Vue Hydrogels, local inflammatory reactions, infection (including abscess), urinary retention, urgency, constipation (acute, chronic, or secondary to outlet perforation), rectal tenesmus/muscle spasm, mucosal damage, ulcers, fistula, perforation (including prostate, bladder, urethra, rectum), necrosis, allergic reaction (localized or more severe reaction, such as anaphylaxis), embolism (venous or arterial embolism is possible and may present outside of the pelvis, potentially impacting vital organs or extremities), syncope and bleeding. The occurrence of one or more of these complications may require treatment or surgical intervention. URO-989811-AB.

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