LAUSR

86Background: In high-risk prostate cancer, the risk of occult lymph node metastases in the pelvic lymph nodes can be as high as 40%. However, the use of whole pelvis radiotherapy (WPRT) in high-risk patients remains controversial with mixed retrospective evidence and two negative prospective trials. Data from a national UK database of patients treated with external-beam radiotherapy (EBRT) and high-dose rate (HDR) brachytherapy was reviewed to evaluate the benefit of pelvic treatment. Methods: From 2009 to 2013, 755 patients with intermediate- and high-risk prostate cancer (clinical stage ≥T2c, Gleason score ≥7 or presenting prostate-specific antigen (pPSA) ≥10) were treated with EBRT and HDR brachytherapy. The pelvic nodes to the level of the common iliac chain were treated in 370 patients with a dose of 46Gy in 23 fractions. The remaining 385 patients received radiotherapy to the prostate only (PORT) at a dose of 37.5Gy in 15 fractions. A single dose of 15Gy was delivered with HDR brachytherapy in each...