This is a multi-institution, randomized, non-inferiority Phase II trial comparing external beam radiotherapy delivered as 54 Gy in 20 fractions to prostate bed +/- 44 Gy in 20 fractions to pelvic lymph nodes delivered daily with external beam radiotherapy delivered as 30 Gy in 5 fractions to prostate bed +/- 25 Gy in 5 fractions to pelvic lymph nodes delivered on alternate days.

Inclusion Criteria:

1. Age >/= 18 years
2. Able to provide informed consent
3. Histologic diagnosis of prostate adenocarcinoma
4. ECOG performance status 0-1
5. Previous radical prostatectomy > 6 months prior to radiotherapy start date
6. Planned to receive post-operative radiation

Exclusion Criteria:

1. Prior pelvic radiotherapy
2. Contraindications to radiotherapy
3. Confirmed metastases (if scan has been done for clinical care)
4. Participants with visible disease in the prostate bed or pelvic lymph nodes on imaging are not eligible for treatment on study.