High-Dose Brachytherapy in Treating Patients With Prostate Cancer

Inclusion Criteria: * Documented pathologic confirmation of prostate adenocarcinoma * Clinical T-classification T1-3 * PSA \< 150 ng/mL * Gleason score 6-10 * Clinically negative lymph nodes as established by abdomino-pelvic CT. CT only for clinical classification of T3 (with contrast if renal function is acceptable; a non-contrast CT is permitted if the patient is not a candidate for contrast), magnetic resonance imaging (MRI), nodal sampling, or dissection. Patients with lymph nodes equivocal or questionable by imaging are eligible if those nodes are \<1 cm in short axis diameter. \[56\] * No evidence of bone metastases (M0) on bone scan, only for PSA \>20 ng/mLor Gleason ≥8, (NaF PET/CT is an acceptable substitute). Equivocal bone scan findings are allowed if plain films and/or MRI are negative for definite metastases. * American Urological Association Symptom Index (AUA SI) =\< 20 Exclusion Criteria: * Clinical T4 disease * PSA \>= 150 ng/mL * AUA SI \> 20 * History of radical prostatectomy, external beam radiotherapy (EBRT), or BT for prostate cancer * Previous chemotherapy for any malignancy, if given within three years of registration * History of rectal surgery * History of rectal fistula * History of inflammatory bowel disease * Severe, active co-morbidity, defined as follows: * Unstable angina and/or congestive heart failure requiring hospitalization within the last six months * Transmural myocardial infarction within the last six months