Anatomic considerations in radiotherapeutic management of bladder cancer

From July 1975 to December 1981, a total of 47 patients with intact bladders had pelvic CT scans. All patients had biopsy-proven bladder cancer. Utilizing CT scans, we measured the bladder extensions in three dimensions. Evacuation of the bladder prior to each treatment is, according to our survey of 48 radiotherapy departments, a rarely practiced procedure. Therefore, it was reasonable to assume that the partially distended bladder, as seen on CT scans, is the target volume for definitive radiotherapy of bladder cancer as practiced in most departments. Analysis of our results indicates that routinely recommended booster ports of 8 X 8, 10 X 10, and 12 X 12 cm would result in gross misses in approximately 50%, 26%, and 7% of patients, respectively. It would appear that geographic misses might contribute significantly to the high incidence of local failures usually reported for definitive radiotherapy in carcinoma of the bladder.