Targeting a full radiation dose to a bladder tumour, with an 80% dose to the surrounding uninvolved bladder tissue, has no obvious detriment to local disease control or survival compared with a full radiation dose to the whole bladder. A multicentre phase III trial demonstrated a low overall incidence of late toxicity (13%), with no significant difference between patients receiving standard radiotherapy (n = 108) and those on the reduced dose protocol (n = 111).