This phase III trial studies compares CT-guided stereotactic body radiation therapy and MRI-guided stereotactic body radiation therapy (SBRT) in treating prostate cancer. Image-guided SBRT is a standard treatment for prostate cancer, which combines imaging of the cancer within the body with the delivery of therapeutic radiation doses produced on a linear accelerator machine. Imaging modalities for image-guided SBRT can be either computed tomography imaging (CT), magnetic resonance imaging (MRI), or a combination of the two. This research is being done to help determine whether there are benefits to MRI-guidance over CT-guidance in patients who are receiving the same radiation dose by SBRT to treat prostate cancer.

PRIMARY OBJECTIVE:

I. To determine whether (MRI)-guided stereotactic body radiotherapy (SBRT) improves acute physician-scored genitourinary (GU) toxicity when compared with standard computed tomography (CT)-guided SBRT for prostate cancer (PCa).

SECONDARY OBJECTIVES:

I. To determine whether there are differences in acute grade >= 2 gastrointestinal (GI) toxicity as assessed by the Common Terminology Criteria for Adverse Events (CTCAE) version 4.03 scale, following MRI-guided SBRT versus CT-guided SBRT.

II. To determine whether there are differences in 5-year cumulative incidences of late grade >= 2 GU and GI physician-reported toxicity, following MRI-guided SBRT versus CT-guided SBRT.

III. To quantify the temporal changes in patient-reported quality of life (QOL) outcomes, as assessed by the Expanded Prostate Cancer Index-26 (EPIC-26), International Prostate Symptom Scores (IPSS), and Sexual Health Inventory for Men (SHIM) QOL indices, following MRI-guided SBRT.

IV. To determine whether there are differences in 5-year biochemical recurrence-free survival (BCRFS) following MRI-guided SBRT.

V. To observe the proportion of SBRT fractions for which on-line adaptive radiotherapy is required due to changes in organ-at-risk anatomy.

OUTLINE: Patients are randomized to 1 of 2 groups.

GROUP I: Patients undergo 5 fractions of CT-guided SBRT over 14 days in the absence of disease progression or unacceptable toxicity.

GROUP II: Patients undergo 5 fractions of MRI-guided SBRT over 14 days in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed up every 3 months for 1 year, every 6 months for 4 years, and then yearly thereafter.

Inclusion Criteria:

• Histologically confirmed, clinical localized adenocarcinoma of the prostate

• No evidence of disease beyond the prostate and/or seminal vesicles (i.e., no suspicious pelvic lymph nodes or presence of metastatic disease outside the pelvis)

• Staging workup as recommended by the National Comprehensive Cancer Network (NCCN) on the basis of risk grouping:

  • Low risk: No staging workup required
  • Favorable intermediate-risk: CT abdomen/pelvis if Memorial Sloan Kettering Cancer Center (MSKCC) nomogram predicts >10% probability of lymph node involvement
  • Unfavorable intermediate-risk: technetium bone scan, CT abdomen/pelvis if MSKCC nomogram predicts >10% probability of lymph node involvement
  • High-risk: technetium bone scan, CT abdomen/pelvis if MSKCC nomogram predicts >10% probability of lymph node involvement
  • Advanced imaging studies (i.e. prostate-specific membrane antigen positron emission tomography [PSMA PET] and axumin scan) can supplant a bone scan if performed first

• Ability to understand, and willingness to sign, the written informed consent

Exclusion Criteria:

• Patients with neuroendocrine or small cell carcinoma of the prostate

• Patients with any evidence of distant metastases. Note, evidence of lymphadenopathy below the level of the renal arteries can be deemed loco regional per the discretion of the investigator

• Prior cryosurgery, high intensity focused ultrasound (HIFU) or brachytherapy of the prostate

• Prior pelvic radiotherapy

• History of Crohn's disease, ulcerative colitis, or ataxia telangiectasia

• Contraindications to MRI, including:

  • Electronic devices such as pacemakers, defibrillators, deep brain stimulators, cochlear implants;
  • Metallic foreign body in the eye or aneurysm clips in the brain;
  • Severe claustrophobia

Patients receiving stereotactic body radiation therapy for the treatment of prostate cancer at the University of California, Los Angeles