We conducted a multicenter randomized trial in the United Kingdom to determine the efficacy of radical radiotherapy in reducing the incidence of progression of pT1G3 transitional cell carcinoma of the bladder to muscle invasive disease and subsequent disease fatality.

Patients with a new diagnosis of pT1G3 NXM0 transitional cell carcinoma with unifocal disease and no carcinoma in situ (group 1), or with multifocal disease and/or carcinoma in situ (group 2) were eligible for the trial. Patients in group 1 were randomized between observation and radiotherapy to the bladder, and in group 2 between intravesical therapy and radiotherapy.

From September 1991 to February 2003 a total of 210 patients from 37 centers in the United Kingdom were entered into the study. There were 77 patients in group 1 and 133 patients in group 2, and 6 patients were excluded from analysis because they were found to have pT2 disease by the reference pathologist. No evidence of an advantage with radiotherapy was found in terms of progression-free interval (hazard ratio 1.07; 95% CI 0.65, 1.74; p = 0.785), progression-free survival (hazard ratio 1.35; 95% CI 0.92, 1.98; p = 0.133) or overall survival (hazard ratio 1.32; 95% CI 0.86, 2.04; p = 0.193).

To our knowledge this is the largest randomized trial performed in patients with pT1G3 disease for which 210 patients were recruited during 11 years. There is no evidence that radiotherapy is better than more conservative treatment. The prognosis of this group of patients appears to be poor irrespective of treatment and new treatment strategies need to be investigated.