BACKGROUND: Salvage radiation therapy and surveillance for low risk PSA recurrence have competing risks and benefits. The efficacy of early salvage radiation therapy to the prostate bed with or without pelvic lymph nodes compared to surveillance in patients with prostate specific antigen (PSA) recurrence following radical prostatectomy and no identifiable recurrent disease evident on prostate specific membrane antigen-positron emission tomography/computerised tomography (PSMA-PET/CT) is …