Eligibility

Eligible Ages

Over 18 Years

Eligible Sex

Male

Accepts Healthy Volunteers

No

Criteria

Inclusion Criteria:

- Documentation of Disease

o Patients must have pathologically confirmed prostate adenocarcinoma.

- Definition of Disease

- Grade Group (GG) 1, 2, or 3.

- PSA less than 20 ng/mL prior to starting ADT, if used.

- Clinical stage of TX, T1 or T2 on digital rectal examination. May have up to
radiological stage T3a on MRI. MRI must be performed within 12 months of
randomization.

- MRI-visible tumor(s), all having PIRADS v2 scores of 3, 4, or 5. Each tumor
should be able to be delineated on T2 and diffusion-weighted imaging (DWI) +/-
dynamic contrast-enhanced imaging (DCE).

- Tumor nodule visible on MRI should be considered able to be boosted by treating
clinician (ie meet urethral constraints while maintaining mandatory GTV
coverage) and <2.5cm in maximal dimension.

- The MRI-defined lesion must be confirmed as malignant on biopsies (Grade group
1, 2, or 3).

- Patients can be concurrently treated with androgen deprivation therapy (ADT) if
this would be standard of care. LHRH analogues, LHRH agonists or Bicalutamide
are permitted. ADT is not mandatory where this would usually be omitted.
Patients needing greater than 6 months of ADT due to disease parameters should
be excluded.

- No high grade disease (GG3) occult to MRI-defined lesion. As a guide, any
pathology for which you would consider surveillance (e.g. GG1, low volume GG2)
is allowed outside of the MRI-defined area.

- No contraindications to MRI (e.g. pacemaker, potentially mobile metal implant,
claustrophobia).

- Prostate volume less than or equal to 90mL.

- No evidence of nodal or distant metastatic disease.

- Prior Treatment

o No history of previous radiation to the prostate, prostate surgery (including
transurethral resection of the prostate (TURP)), or other local prostate cancer
treatments.

- Age ≥ 18

- ECOG Performance Status of ≤ 2 (See Appendix I for performance status criteria)

- Required Organ Function

- Adequate hematologic function defined as follows:

- Absolute neutrophil count (ANC) ≥ 1,500 cells/mm3

- Platelets ≥ 100,000 cells/mm3

- Hemoglobin ≥ 8 g/dl

- Adequate renal function defined as follows:

- Creatinine clearance (CrCL) of ≥30 mL/min by the Cockcroft-Gault formula:

CrCl (mL/min) = [140 - age (years)] x weight (kg) / 72 x creatinine (mg / dL) {x 0.85 for
female patients}

- Adequate hepatic function defined as follows:

- Total bilirubin ≤ 1.5 x institutional upper limit of normal (ULN) (patients
with known Gilbert's disease who have bilirubin level ≤ 3 x ULN may be
enrolled)

- AST and ALT ≤3 x institutional ULN

- Adequate cardiac function defined as follows:

- Patients with known history or current symptoms of cardiac disease, or history
of treatment with cardiotoxic agents, should have a clinical risk assessment of
cardiac function using the New York Heart Association Functional
Classification.

- To be eligible for this trial, patients should be class 2B or better (see
Appendix II: New York Heart Association (NYHA) Functional Classification).

- Comorbid Conditions

- No active infection requiring parenteral antibiotic(s).

- Patients with a prior or concurrent malignancy whose natural history or treatment
does not have the potential to interfere with the safety or efficacy assessment of
the investigational regimen are eligible for this trial.

- No severe GU symptoms that would preclude extreme hypofractionation per the
discretion of the treating physician.

- No IPSS Score greater than 19.

- No comorbidities which predispose to significant toxicity (e.g. inflammatory bowel
disease) or preclude long term follow up.

- Ability of the participant to understand and the willingness to sign a written
informed consent form.

- Willing to consent to contraception during and for 1 year after treatment when
applicable.

- Ability/willingness to comply with the patient reported outcome questionnaires
schedule throughout the study.