Trial Evaluating the Safety and Efficacy Of MR-Linac-Guided Radiotherapy as Salvage Treatment After External Beam Radiotherapy Recurrence (TUMORNATOR II)

Inclusion criteria

• 18 years of age or older male participants
• Biopsy proven intraprostatic prostate cancer after prior definitive external beam radiotherapy (moderate hypofractionation or Stereotactic Body Radiation Therapy (SBRT) acceptable).
• a. NOTE: Seminal vesicle involvement allowed
• Pathology confirming recurrent disease must have evidence of viable cancer as indicated with pathology interpretation where a Gleason score can be assigned
• Serum testosterone ≥ 50 ng/dL determined within 2 months prior to enrollment
• a. Prior Androgen Deprivation Therapy (ADT) use acceptable if testosterone level \>50ng/dL
• At least 4 weeks must have elapsed from major surgery
• Karnofsky Performance Scale (KPS) ≥ 80% or Eastern Cooperative Oncology Group (ECOG) 0-1
• Prostate size as determined on MRI to be \< 90 cc.
• International Prostatism Symptom Score (IPSS) ≤ 20
• Patient must be available for follow-up. After 2 years of follow-up, upon completion of post-treatment biopsy, telephone, and chart review-based follow-up will be acceptable for up to 5 years
• Presence of a T2 and/or DWI-visible prostatic lesion on mpMRI
• a. NOTE: Lesion visible on MRI required for enrollment but PSMA/PET avid lesion not required
• Satisfy all MRI screening criteria and be willing to fill out the standard MRI screening form

Exclusion criteria

• History of prostate brachytherapy (low dose rate or high dose rate)
• Actively undergoing androgen deprivation therapy and/or anti-androgens at time of enrollment
• CT or MRI or PET scan evidence of extraprostatic disease
• Patients with one or more positive lymph nodes considered suspicious as determined by clinical assessment on MRI or CT or PET scan
• History of another malignancy within the previous 2 years except for the following: adequately treated basal cell or squamous cell skin cancer, superficial bladder cancer, currently in complete remission, or any other cancer that has been in complete remission for at least 3 years
• Patients with Crohn's disease or ulcerative colitis
• MRI ineligibility due to: the presence of a cardiac pacemaker, defibrillator, or other implanted metallic or electronic device which is considered MR unsafe; severe claustrophobia; inability to lie flat for the duration of the study; etc.
• Metallic implant or device in the pelvis that might distort the local magnetic field and compromise quality of mp-MRI
• Lateral pelvic separation greater than 50 cm and/or anterior-posterior separation greater than 35 cm which are incompatible with MRCAT reconstruction
• Contra-indications to receiving gadolinium contrast or PSMA radioligand
• Karnofsky Performance Scale (KPS) \< 80 or ECOG 2+
• Grade 3 or higher toxicity experienced after the initial course of External Beam Radiation Therapy (EBRT)
• Disease free interval \< 2 years
• Hx of Transurethral Resection Of Prostate (TURP) within the year
• Prior high-intensity focused ultrasound (HIFU) or Cryotherapy
• Prior history of urethral stricture
• Unable to give informed consent
• Unable to complete quality of life questionnaires