This phase I trial studies the side effects and the best dose of hypofractionated stereotactic body radiation therapy (SBRT) in treating patients with prostate cancer that was removed by surgery. Hypofractionated SBRT delivers higher doses of radiation therapy over a shorter period of time and may kill more tumor cells and may have fewer side effects than standard radiation therapy.

PRIMARY OBJECTIVES:

I. To determine maximum tolerated dose-per-fraction for SBRT to the prostate fossa following prostatectomy based on acute toxicity (< 90 days).

SECONDARY OBJECTIVES:

I. To describe the acute (< 90 days) toxicities and adverse events associated with hypofractionated SBRT when administered to the prostate bed in the post-prostatectomy setting.

II. To describe the late (> 90 days from treatment) toxicities and adverse events associated with hypofractionated SBRT when administered to the prostate bed in the post-prostatectomy setting.

TERTIARY OBJECTIVES:

I. To describe the patient-reported toxicity/quality of life (QOL) following hypofractionated SBRT treatment.

OUTLINE: This is a dose-escalation study.

Patients undergo 5, 10, or 15 fractions of hypofractionated SBRT daily over 1-3 weeks.

After completion of study treatment, patients are followed up at 2, 6, and 13 weeks and then at 6, 9, 12, 18, 24, 30 and 36 months.

Inclusion Criteria:

• Adenocarcinoma of the prostate treated primarily with radical prostatectomy

  • Any type of radical prostatectomy is permitted including retropubic, perineal, laparoscopic or robotically assisted; there is no time limit for the date of radical prostatectomy

• One of the following pathologic classifications

  • T3N0 disease with or without a positive surgical margin or

  • T2N0 disease with or without a positive surgical margin

    • Those with T2N0 disease and a negative margin must have a detectable prostate-specific antigen (PSA) following radical prostatectomy or
    • Must have had an undetectable PSA after prostatectomy and has since had a rise in post-operative PSA to 0.2 ng/mL or greater

• Zubrod performance status of 0 -1

• No distant metastases, based on the following workup within 60 days prior to registration

  • Magnetic resonance imaging (MRI) of the pelvis
  • Bone scan or sodium fluoride positron emission tomography (PET), that if suspicious has MRI or plain X-rays to rule out bone metastasis

• Patients can be on androgen deprivation therapy

• Ability to understand and willingness to sign a study-specific informed consent prior to study entry

Exclusion Criteria:

• N1 patients are ineligible, as are those with lymph node (LN) enlargement > 1.5 cm by computed tomography (CT) or MRI of the pelvis, unless the LN is biopsy proven to be negative

• Gross residual disease in the prostate fossa appreciated wither on digital rectal examination (DRE) or on imaging, unless biopsy proven not to contain cancer

• Patients who were exposed to neoadjuvant chemotherapy or chemotherapy after prostatectomy

• Prior radiation of any kind to the prostate gland or pelvis

  • Prior brachytherapy is not allowed

• History of inflammatory colitis or other active severe comorbidities

• Patients who are on immunosuppressant medication