One of the usual approaches to treating intermediate-risk prostate cancer is a type of radiation therapy called SBRT (stereotactic body radiation therapy). SBRT delivers higher than standard doses of radiation over a lower number of treatment sessions. However, there is a 20% chance that intermediate-risk prostate cancer will come back after this treatment. The purpose of this study is to find out whether giving an even higher dose (a "boost" dose) of radiation directly to the main tumor and the standard dose of radiation to the rest of the prostate may cure the cancer or prevent it from coming back for a longer period of time while causing few side effects.

Inclusion Criteria:

• Intermediate-risk prostate cancer patients will be eligible for this study. Risk groups will be assigned as per NCCN guidelines. Intermediate-risk patients will be defined as:

  • PSA 10-20 ng/ml or
  • Gleason score = 7 or
  • Clinical stage T2b/T2c or

• Additionally, patients will be required to meet all of the following criteria:

  • Age ≥ 18
  • Karnofsky Performance Status (KPS) ≥ 80 (Appendix 1)
  • Prostate size ≤ 80 cc
  • Presence of a T2-visible prostatic lesion with maximum dimension of ≥ 0.5 cm and no more than one additional disease focus
  • MRI findings: Lesion may contact the capsular edge, possible extracapsular extension (ECE) permitted
  • International Prostate Symptom Score ≤ 15
  • Satisfy all MRI screening criteria and be willing to fill out the standard MRI screening form

Exclusion Criteria:

Patient will be excluded if they meet any one of the following criteria:

• Gleason score >7

• PSA >20

• Prior or concurrent androgen deprivation therapy for prostate cancer MRI findings: suspicious for/probable ECE

• MRI findings: >2 disease foci identifiable

• Evidence of metastatic disease on bone scan or MRI/CT

• 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

• KPS < 80

• Pelvic or prostate MRI or CT (MRI preferred) evidence of radiographic T3, T4, or N1 disease

• Prior history of transurethral resection of the prostate

• Prior history of urethral stricture

• Prior history of pelvic irradiation

• History of inflammatory bowel disease

• Unable to give informed consent

• Unable to complete quality of life questionnaires

• Abnormal complete blood count, including any of the following:

  • Platelet count less than 75,000/ml
  • Hb level less than 10 gm/dl
  • WBC less than 3.5/ml

• Abnormal renal function tests (creatinine > 1.5)

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.