RADIOTHERAPY FOR T2 AND T3 CARCINOMA OF THE BLADDER - THE INFLUENCE OF OVERALL TREATMENT TIME

The influence of overall treatment time on local control rate was stud ied on a group of 147 patients with muscle invasive T2 or T3 transitio nal cell carcinoma of the urinary bladder. All patients received exter nal radiotherapy at the Catharina Hospital, Eindhoven, The Netherlands between January 1974 and December 1984. Patients treated with overall treatment times shorter than 75 days (n = 92) were irradiated during a continuous course; all but one patient, with overall treatment times of 75 days or more (n = 55), received split-course radiotherapy. Actu arial local relapse-free probability at 3 years (LRFP(3)) was computed from the onset of radiotherapy. LRFP(3) proved to be dependent on ove rall treatment time. For T2 stage, LRFP(3) was 80 +/- 18% (n = 5) and 54 +/- 13% (n = 13) for overall times between 15-44 and 45-74 days, re spectively, 36 +/- 14% (n = 11) for overall times between 75 and 104 d ays and 64 +/- 15% (n = 11) for overall times longer than 105 days. Fo r T3 stage, LRFP(3) was 33 +/- 19% (n = 6) and 48 +/- 10% (n = 25) for overall times between 15-44 and 45-74 days, respectively, 25 +/- 14% (n = 12) for overall times between 75 and 104 days and 22 +/- 14% (n = 9) for overall times longer than 105 days. The figures between bracke ts are numbers of patients relapsing within 3 years or at risk of rela pse during at least 3 years. Patients who died without local relapse b efore 3 years were censored, We have reasons to believe that patient s election bias leads to overestimation of LRFP(3) for the split-course radiotherapy in retrospective studies where the 'intention to treat' c annot be recalled. This retrospective study suggests that prolonging o verall time of radiotherapy has an effect on local control in T2 and T 3 transitional cell carcinoma of the urinary bladder. Local control wa s the worst for patients treated by split-course radiotherapy with a g ap of approximately one month. Local control was not further decreased (and seemed even improved) by longer gaps, but this observation is po ssibly biased as explained in the discussion section. For patients tre ated by continuous course radiotherapy we could not find a difference in local control rates between patients treated with overall times of 44 days or less and those treated with overall times of 45-74 days.