A feasibility study of accelerated fractionation in radiotherapy of carcinoma of the urinary bladder

Abstract

Purpose : To establish the shortest possible overall treatment time, with respect to acute and late toxicity, in which a radiation dose of 66 Gy in 2 Gy/fraction can be administered to the urinary bladder. Methods and Materials : In a stepwise fashion the overall treatment time of our routinely used conventional treatment schedule (66 Gy in 2 Gy/fraction in 6.5 weeks) was reduced to 5 weeks (Step 1) and then 4 weeks (Step 2). Shortening of the overall treatment time was obtained by giving two daily fractions during the last part of the treatment. The interfraction interval was a minimum of 6 h. Toxicity was scored according to a modified scheme of the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer. Fifteen patients received the 5-week schedule and 25 patients received the 4-week schedule. Results : Note that feasibility was very good for the 5-week schedule. No Grade ≥3 acute bowel or bladder toxicity was seen in these patients. Severe late complications did not occur. In the 4-week schedule, acute bladder toxicity was unaffected but acute bowel toxicity was considerably increased. Of the 25 patients, 16 suffered from Grade 3 toxicity, 3 from Grade 4, and 1 from Grade 5 toxicity. Actuarial analysis at 3 years showed a 31% incidence of Grade 4 late bladder complications. Conclusion : It is concluded that the 5-week schedule is well tolerated. In contrast, the 4-week schedule shows unacceptable acute bowel toxicity and an increased incidence of late bladder comlications ( p = 0.043).