The BioProtect Balloon Implant™ System is 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 the balloon to reduce the radiation dose delivered to the anterior rectum. The balloon composed of a biodegradable material that maintains that space for the entire course of prostate radiotherapy treatment and is completely absorbed by the patient's body over time.

This study will be a prospective, multi-center, randomized, double-arm, single blind, concurrently controlled study to assess the safety and efficacy of the balloon in prostate cancer subjects undergoing radiotherapy by means of intensity modulation radiation therapy (IMRT).

Inclusion Criteria:

• Be at least 18 years of age
• Have been histologically diagnosed with invasive adenocarcinoma of the prostate, at clinical stage T1-T3 (as determined by a biopsy taken within 9 months of the screening visit)
• Be scheduled for radiation therapy (XRT) by means of IMRT

Exclusion Criteria:

• Any prior invasive malignancy (except non-melanomatous skin cancer) unless the subject has been disease free for a minimum of 5 years
• Prior radical prostatectomy
• Prior cryosurgery or radiotherapy for prostate cancer, or other local therapy for prostate cancer
• Prior radiotherapy to the pelvis, including brachytherapy
• History of prior surgery involving the rectum or anus
• Prior surgical procedure involving the peri-rectal and/or peri-prostatic area

Study subjects are blinded to group assignment.