High Dose-Rate Brachytherapy and Stereotactic Body Radiotherapy for the Treatment of Prostate Adenocarcinoma

Inclusion Criteria:

* Ability to understand a written informed consent document, and the willingness to sign it
* Age \>= 18 years
* Eastern Cooperative Oncology Group (ECOG) performance status 0-2
* History/physical examination with digital rectal examination of the prostate within 8 weeks prior to registration
* Histologically confirmed intermediate- to high-risk prostate adenocarcinoma (T1c-T3b, PSA \> 10, and/or Gleason score \>= 7
* No evidence of disease beyond the prostate and/or seminal vesicles (i.e., no suspicious pelvic lymph nodes or presence of metastatic disease outside the pelvis)
* Prostate size =\< 60cc
* International Prognostic Scoring System (IPSS) score =\< 15
* Able to safely receive moderate sedation or general anesthesia

Exclusion Criteria:

* Patients with neuroendocrine or small cell carcinoma of the prostate
* Prior or concurrent invasive malignancy (except non-melanomatous skin cancer) or lymphomatous/hematogenous malignancy unless continually disease free for a minimum of 5 years
* Regional lymph node involvement
* Evidence of distant metastases
* Previous radical surgery (prostatectomy) or cryosurgery or high-intensity focused ultrasound for prostate cancer
* Previous pelvic irradiation or prostate brachytherapy
* Previous or concurrent cytotoxic chemotherapy for prostate cancer
* Patients with history of inflammatory bowel disease (i.e., Crohn's disease, ulcerative colitis), high predisposition for radio-toxicity compared to general population (i.e., ataxia telangiectasia), or at risk for major bowel surgery
* Transurethral resection of the prostate (TURP) procedure within 6 months of radiation treatment