Prof Malcolm Mason discusses the results of an intergroup study - carried out by the UK Medical Research Council (MRC), the National Cancer Institute of Canada (NCIC) and the Southwest Oncology Group (SWOG) from the United States - looking at patients with locally advanced prostate cancer or high risk localised prostate cancer who would normally be treated with androgen deprivation therapy (ADT). This trial compared ADT alone with ADT plus radiotherapy and conclusively demonstrated the benefit of adding radiotherapy to ADT. Prof Mason speaks about the level of side effects experienced by the patients and looks forward to the results of the ongoing NCRI CHHIP study into hypofractionated radiotherapy.