Effectiveness of the SpaceOAR Vue System in Subjects With Prostate Cancer

Inclusion Criteria:

* Age ≥ 18 years old.
* Subjects must have pathologically confirmed (by routine hematoxylin and eosin (H\&E) staining) invasive adenocarcinoma of the prostate and been planning to undergo SBRT.
* Subjects must have intermediate risk prostate cancer as defined by the presence of one or more of the following:
* Clinical Stage T2b - T2c (AJCC 6th edition) tumor
* Gleason Score 7 as determined from a biopsy taken within 9 months preceding Enrollment (randomization)
* Demonstrated blood PSA levels 10-20 ng/ml as measured within 6 months preceding Enrollment (randomization) and prior to commencing androgen deprivation therapy (ADT)
* Subject or authorized representative was informed of the nature of the study and provided written informed consent, approved by the appropriate Institutional Review Board (IRB)/Ethics Committee (EC) of the respective clinical site.

Exclusion Criteria:

* Prostate \>80 cc documented within 9 months preceding Enrollment (randomization)
* Clinical stage T3 or T4 (AJCC 6th edition) tumor
* Blood PSA level \>20 ng/ml as measured within 6 months preceding Enrollment (randomization) and prior to commencing androgen deprivation therapy (ADT)
* Gleason Score ≥ 8 as determined from a biopsy taken within 9 months preceding Enrollment (randomization)
* Subjects who had MRI evidence of gross posterior extracapsular extension (ECE) of the prostate cancer. (Note: MRI should be from within 9 months preceding Enrollment (randomization). If MRI is contraindicated, a digital rectal exam may be performed to confirm the absence of gross posterior ECE)
* Subjects who had metastatic disease, other ongoing cancers which were treated during the study or subjects for whom pelvic lymph node radiotherapy was planned.
* Subjects with any prior invasive malignancy (except non-melanomatous skin cancer) unless the subject had been disease free for a minimum of 3 years.
* History of prostatectomy, transurethral prostate surgery (e.g. TUNA, TUMT, TURP) if performed within 1 year prior to screening, other local prostate cancer therapy (e.g., cryotherapy or brachytherapy) or previous pelvic irradiation at any time prior to screening.
* History of prior pelvic surgery requiring low anterior or abdominoperineal resections or rectal surgery.
* History of or active inflammatory bowel disease (IBD) such as Crohn's disease or ulcerative colitis.
* History of or current perirectal disease that may interfere with interpretation of study outcomes including anal or perianal diseases such as fistula.
* Bleeding hemorrhoids requiring medical intervention within the prior three months.
* Diagnosed active bleeding disorder or a clinically significant coagulopathy. Note: Patients on anticoagulants may be included if the anticoagulant medication can be discontinued for index procedure.
* Active inflammatory or infectious process involving the perineum, gastrointestinal (GI) or urinary tract based on positive diagnosis or suspected diagnosis in the presence of fever \>38⁰ C, WBC \> 12,000/uL.
* Compromised immune system or prior diagnoses for human immunodeficiency virus (HIV) (with a detectable viral load within the last 6 months)/acquired immunodeficiency syndrome (AIDS) or autoimmune disease.
* If a subject was enrolled in another investigational drug or device trial that had not completed the primary endpoint or that clinically interfered with this study.
* Unable to comply with the study requirements or follow-up schedule.
* Any condition the Investigator believed would interfere with the intent of the study or would make participation not in the best interest of the patient.
* Known iodine sensitivity or allergy
* Known polyethylene glycol (PEG) sensitivity or allergy