Could two radiation doses beat five for prostate cancer?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * • Age 18 or older. * Able to provide informed consent. * ECOG performance status 0 - 2. * Fit for all protocol treatment and follow-up. * Life Expectancy \> 5 years. * Histologically confirmed adenocarcinoma of the prostate, NCCN low or intermediate risk, with biopsy performed within the last 18 months: Low risk = cT1-T2a,Gleason ≤ 6, and PSA \< 10ng/mL. Intermediate risk = at least one of: cT2b/T2c, PSA 10-20ng/mL, or Gleason 7, but not high risk. * 6 months of Androgen Deprivation Therapy (ADT) is permitted for those with NCCN unfavorable intermediate risk disease (aka high-tier intermediate risk disease), defined as intermediate risk disease with one or more of: two or three intermediate risk features, Gleason 4+3, or ≥50% biopsy cores positive. * For those with NCCN unfavorable intermediate risk disease, it is permitted for ADT to have been initiated prior to study enrollment provided it is possible for radiotherapy to be completed before completion of 6 months of ADT. * Prostate volume \<100cc based on imaging or digital rectal examination. * PSA within 90 days prior to registration. If ADT is started before registration, then the PSA must have been done no more than 90 day prior to the date of the first ADT injection. * CT abdomen and pelvis within the 6 months prior to registration (may be omitted for NCCN low risk participants). If particpant started on ADT prior to registration, CT should be done before first ADT injection. * Bone scan within the 6 months prior to of registration (may be omitted for NCCN low risk participants). If particpant started on ADT prior to registration, bone scan should be done before first ADT injection. * Must be appropriate for and willing to undergo implantation of prostate fiducial markers and Space OAR Hydrogel. Exclusion Criteria: Clinical stage cT3 or greater. Gleason score 8 or greater. PSA \> 20ng/mL or greater. NCCN high or very high risk. Pelvic nodal metastases. Distant metastases. Previous malignancy within the last 5 years except basal or squamous cell carcinomas of the skin. Previous pelvic radiotherapy. Any prior active local treatment for prostate cancer. Participants previously on active surveillance are eligible if they continue to meet all other eligibility criteria. Unilateral or Bilateral hip prostheses. Medical conditions likely to make radiotherapy inadvisable (e.g., inflammatory bowel disease). Medical condition that would make implantation of fiducial markers or hydrogel rectal spacer unsafe, in the opinion of the treating physician (e.g., pelvic or prostate abscess). Medical condition or implant that prohibits MRI (e.g. pacemaker) Trans-urethral resection of the prostate (TURP), GreenLight Laser or Holmium Laser Prostate procedure within 6 months of radiotherapy.