- Arm I (immediate RT): Within 2 months after randomization, patients undergo radiotherapy to the prostate bed once a day, 5 days a week, for 4 (20 fractions total) or 6.5 weeks (33 fractions total). They may also undergo radiotherapy to the pelvic lymph nodes once a day, 5 days a week, for 4.5 weeks (23 fractions total) at the investigator's discretion.