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Prostate Cancer Treatments: What Is SpaceOar?


  • What is SpaceOAR? SpaceOAR stands for Space Organ at Risk.
  • SpaceOAR is a hydrogel spacer doctors use to protect patients’ rectums during radiation therapy for prostate cancer.
  • By injecting the hydrogel between the prostate and rectum, doctors create valuable separation.
  • Doctors rely more and more on SpaceOAR to protect the organs around patients’ prostates.

SpaceOAR is an injectable solution for shielding the rectum from the effects of radiation therapy for prostate cancer. The prostate is close to the wall of the rectum. When radiation hits the prostate during therapy, it also affects the rectum. SpaceOAR creates distance between the two organs, protecting the rectum from radiation. 

What is SpaceOAR, and how does it Work?

SpaceOAR is a hydrogel spacer that absorbs water and retains its shape. It uses natural hydrogels. Hyaluronic acid is a natural hydrogel that gives volume and elasticity to the skin, among other functions. 

Doctors inject SpaceOAR into the space between the prostate and the rectal wall. Once there, the substance expands and creates an additional distance of about 1.3 cm between the two organs. This distance is enough to protect the rectal wall from the majority of the radiation hitting the prostate. 

OAR stands for Organ At-Risk, referring to the rectum. 

Radiation-based prostate cancer treatment is now standard. New technologies allow doctors to achieve high precision with radiation. The natural space between the prostate and the rectal wall is too small, however. By increasing this space, SpaceOAR hydrogel creates the separation doctors need to avoid the rectum. 

SpaceOAR Benefits

SpaceOAR hydrogel is a simple and effective solution to a complicated problem. 

Radiation-based prostate cancer treatment is taxing on the body, and if radiation hits other organs, it’s worse. 


Prostate cancer patients who do not receive a SpaceOAR injection before radiation therapy are more likely to develop complications. They may experience more bowel problems and urinary irregularities. Their sexual quality of life may decline as well.

A 2017 study determined that SpaceOAR significantly reduces rectal toxicity in patients receiving radiation therapy for prostate cancer. 

Quality of Life

SpaceOAR significantly improves the self-reported quality of life of patients. Researchers measured good treatment outcomes while preserving patients’ quality of life with SpaceOAR. Only 59 patients took part in the study, however. 


The SpaceOAR insert limits the movements of the prostate in response to urination, flatulence, and other bodily functions involving the area. During a treatment session, doctors prefer a stable prostate. 

A Solution for Diverse Patients

Doctors have used other methods for spacing in prostate radiation therapy, like fiducial markers, or Calypso beacons. They can’t use these solutions for all patients, however. Some do not qualify. 

Large abdominal girth, hip replacements, pacemakers, and various medications disqualify patients from using these more traditional solutions.

SpaceOAR does not contain electronics or drug-like chemicals. It is, therefore, suitable for use in many patients. 

Lasting Benefits

After doctors inject SpaceOAR, they must wait a week for the insert to settle. SpaceOAR then remains in place for at least three months. It creates a comfortable window for doctors to perform several radiation treatments. A treatment course takes several weeks, but typically less than a month. 

The body absorbs and eliminates SpaceOAR in about six months. 


The hydrogel material SpaceOAR uses is mostly water. The body tolerates it well.  And it does not interfere with other treatments and medications. The body absorbs it without problems, eliminating the insert without another intervention. 

Hydrogel is mostly water.


Doctors can use hydrogel spacers with a variety of radiation beams. The method lends itself well to treatments with external beams and internal radiation therapy. For special cases, doctors can even combine the two treatment methods. Stereotactic body radiation therapy is an advanced treatment method relying on high-accuracy imaging and diagnostics. It works well with hydrogel spacers like SpaceOAR. 

SpaceOAR Risks

Inserting an outside substance into the body for three to six months always entails risks and the possibility of discomfort. When the site of the injection is the highly sensitive perineum, these risks multiply. 

Doctors use local anesthesia before injecting SpaceOAR. Transrectal ultrasound guidance allows them to inject the hydrogel exactly where they need it. The injection may still be painful, and the hydrogel material may cause some pain and discomfort before the body accepts its presence. 

Common Complications

The insertion procedure is relatively simple, but does not always go according to plan. The injection may cause: 

  • Needle and hydrogel material penetration into a nearby blood vessel or organ
  • Inflammation of the injection site
  • Infection
  • Injury to the rectum or prostate
  • Urinary retention 

Severe Complications

Researchers have documented several cases of patients experiencing severe complications from SpaceOAR. 

  • Anaphylaxis
  • Prostatic sepsis
  • Abscesses
  • Perineal drainage consisting of puss
  • The injury and erosion of the rectal wall
  • Fistula in the rectum
  • Pulmonary embolism 

Healthcare providers even reported some cases of toxicity and one death. 

Prostate management is a delicate balancing act. Doctors must consider the benefits and risks of every intervention. 

More and more doctors use SpaceOAR. Considering the high number of SpaceOAR interventions, the incidence of adverse events is sparse. We must acknowledge, however, that many of the less severe complications may go unreported. 

SpaceOAR Contraindications

SpaceOAR may not be suitable as a complementary treatment for advanced prostate cancer. When cancer engulfs much of the prostate, doctors can’t create space with the hydrogel insert. Using a needle for injection becomes hazardous as it may spread cancerous cells through healthy tissue. 

Patients who have already received radiation therapy, cryotherapy, or high-intensity ultrasound therapy for prostate cancer are not good candidates for SpaceOAR. 

Patients with blood clotting or bleeding problems are also unsuitable candidates for SpaceOAR.

Doctors will not use a hydrogel spacer in patients who are on anticoagulants. To use SpaceOAR, these patients must discontinue their anticoagulant therapies. 

Inflammatory diseases like prostatitis and anorectal inflammation also disqualify patients from SpaceOAR use. 

Crohn’s disease and ulcerative colitis increase the chance of bleeding. Therefore, doctors won’t use SpaceOAR in patients suffering from these diseases. 

SpaceOAR and Erectile Dysfunction

Now that you can answer the question “what is SpaceOAR?” you probably want to know whether it can help your erections. By protecting the other organs around your prostate, hydrogel spacers can save your erectile function. 

After prostate surgery or radiation therapy, your orgasms and erectile function may suffer. 

Man looking at his crotch with disappointment
ED can happen after prostate surgery.

Fortunately, FDA-approved medications like Cialis and Viagra work in prostate cancer patients. They can help restore and preserve your erections. 

eDrugstore Can Help

We can help you address your erectile dysfunction. We carry generic and brand versions of the most popular FDA-approved erectile dysfunction drugs. 

We offer consultations with U.S.-licensed doctors, who can help you determine the best treatment course for your ED and provide you with the prescriptions you need.

Generic Viagra, Cialis or Propecia