Randomized Trial of Image -Guided Stereotactic Radiation Therapy (IG-SRT) in Prostate Cancer

This is a randomized, two arm study for patients with low-risk or favorable intermediate-risk
prostate cancer as defined by 1.2016 NCCN criteria.

Patients will be randomized to either rectal spacer placement or endorectal balloon
placement, daily prior to each radiation treatment.

1. Endorectal balloon (ERB): Immobilization device manually placed into the rectum prior to
radiation treatment planning CT and daily treatment delivery, to immobilize the prostate
and reduce prostate motion.

2. Rectal spacer (RS): Biodegradable gel that is transperineally injected between the
rectum and prostate under transrectal ultrasound guidance, to increase physical distance
and thereby reduce radiation dose to the anterior rectal wall. The spacer begins to
biodegrade in 2-3 months, and is fully absorbed within 6 months.

This study plans to enroll a total of 40 patients with an accrual period of 4 years.

Inclusion Criteria:

- Biopsy-proven diagnosis of prostate adenocarcinoma, diagnosed within 1 year of
randomization

- Either NCCN-defined low-risk disease (T1c-T2a, Gleason score 3+3=6, PSA <10),
intermediate-risk disease (Gleason score 3+4=7, 4+3=7, T2b-c and/or PSA 10-20; ) or
high-risk disease due to Gleason score 8-10 and/or PSA >20 ng/ml, but not due to T3-T4
disease on physical exam.

Exclusion Criteria:

- History of prior pelvic radiation (external beam or brachytherapy)

- Prior or concurrent lymphomatous/hematogenous malignancy, or history of
prior/concurrent invasive malignancy during the past 5 years

- Very high risk prostate cancer (T3b-T4 on clinical exam, Primary Gleason pattern 5, or
>4 cores with Gleason score 8-10)

- History of prior chemotherapy for prostate cancer

- History of irritable bowel disease

- Evidence of lymph node involvement

- AUA score >15

- Prostate size > 90 cc