This purpose of this study is to evaluate the safety and effectiveness of a technique called focal high-dose-rate (HDR) brachytherapy as treatment for prostate cancer that has come back in the prostate after prior radiotherapy. The study will examine the safety and efficacy of the treatment. The type of radiation that participants in this research will receive is targeted directly at the areas of the prostate where recurrent disease is evident, while avoiding treatment of the normal appearing prostate. This involves the placement of a radioactive material in the affected area of the prostate temporarily, where it remains for a short period of time, and then is subsequently removed using a minimally invasive technique called HDR Brachytherapy.

The goal of any radiation treatment plan is to achieve maximal disease response with minimal toxicity. HDR brachytherapy offers a promising definitive treatment option in the setting of Locally Recurrent Prostate Cancer after prior definitive radiation, based on the limited data described above, with achievement of biochemical disease control in a large percentage of patients with relatively low toxicity. With focal HDR brachytherapy, the investigators can treat the isolated areas of disease, while avoiding normal prostate tissue, with the goal of further improving toxicity rates. The investigators hypothesize that using single fraction, focal HDR brachytherapy performed with one single implant for the treatment of LRPC is feasible and without excess toxicity, and can be safely delivered. This should allow for better patient convenience and cost and improved treatment dosimetry and planning, as it will decrease the risk of catheter displacement between fractions, which will hopefully correlate to less GU and non-GU acute toxicity. The primary objective is to determine the acute and late GU and GI toxicity of single fraction focal HDR salvage brachytherapy (primary endpoint).

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

There is no plan to make individual participant data (IPD) available to other researchers