Inclusion Criteria:

* Biopsy proven locally recurrent adenocarcinoma of the prostate after the completion of definitive radiation therapy for initially diagnosed prostate cancer.

* Biopsy must be performed within 182 days of trial registration
* Biopsy should be a standard sextant biopsy AND either a targeted MR/ultrasound guided biopsy or saturation biopsy or both.
* Initial cancer diagnosis that fits these specific criteria:

* Stages T1-T3a
* Nx or N0
* Mx or M0
* Eligible initial definitive radiotherapy modalities include:
* External beam radiotherapy, with photon or proton beam therapy

* Conventional or moderately hypofractionated radiotherapy
* Extremely hypofractionated external beam radiotherapy (Stereotactic body radiation therapy)
* Definitive Brachytherapy:

* Low-dose rate
* High-dose rate
* Locally recurrent disease confined to the prostate +/- seminal vesicles and immediately adjacent tissue, as evaluated by the following:

* History/Physical examination
* Radiographically node negative disease (N0), as defined by CT or MR of pelvis +/- abdomen within 6 months of registration.
* No evidence of bone metastases (M0) on bone scan within 6 months of registration.
* Fluciclovine-PET is encouraged, but not required
* Patients receiving ADT are eligible as long as they meet the other eligibility criteria. However, the duration of all ADT must be documented.
* Current ECOG Performance status Scale 0-2
* Current International Prostate Symptom Score (IPSS) \< 20
* The patient must be medically suitable to receive general anesthesia.
* The patient must be able and willing to sign a study-specific written informed consent form before study entry.

Exclusion Criteria:

* Preregistration GI or GU toxicity (for any reason) grade ≥ 3 as defined in CTCAE version 4.03. That is, grade ≥ 3 GU or GI toxicity after first course of radiotherapy
* Patients receiving any other investigational agents.
* Uncontrolled inter-current illness including, but not limited to, ongoing or active infection, severely symptomatic congestive heart failure, cardiac arrhythmia, recent myocardial infarction in last 6 months, or psychiatric illness/social situations that could limit compliance with study requirements.
* Patients who have received chemotherapy or immunotherapy within one month prior to study enrollment, other than ADT