The measurement of the regression of carcinoma of the bladder using ultrasonography and CT scanning during and after radical radiotherapy

Abstract

In 50 patients receiving radical radiotherapy for carcinoma of the bladder a well-defined tumour was observed in the bladder either by trans-abdominal ultrasonography or by CT scanning prior to treatment. The histological type was transitional cell carcinoma 46, adenocarcinoma 1 and squamous cell carcinoma 3. The cross-sectional area of the tumour in the transverse plane was measured before the start of radiotherapy. In 37 patients serial measurements were made by ultrasonography during and after radical radiotherapy. In three patients no regression was seen during the first 14–27 days of treatment. In 34 patients with transitional cell carcinoma the median area-halving time was 37 days. Serial measurements of the volume of the tumour before, during and after radiotherapy were made by, CT scanning in 29 patients. In two patients the tumour progressed with a volume-doubling time of 93 and 108 days, respectively. In 25 patients with transitional cell carcinoma the median volume-halving time was 29 days with a median area-halving time of 44 days. Linear-regression analysis of the initial tumour areas (31 patients) as measured by ultrasonography and CT scanning was performed. The correlation coefficient was r = 0.69. The correlation coefficient for the area halving-times measured both by ultrasonography and CT scanning was r = 0.53 (nine patients). Biphasic regression with a second slower phase with area-halving and volume-halving times of several hundred days was observed in six patients. Calcification of the tumour during and after radiotherapy was observed in several patients. No significant change in the CT number of the tumour was observed after radiotherapy. The median initial tumour volume as measured by CT scanning was 38 (7–211) cm 3. The median initial tumour area as measured by ultrasonography was 16 (6–40) cm 2. A tumour of median size with a median halving-time would take 120 days (4 months) to regress completely. Cystoscopy within 6 months of the start of radiotherapy is unlikely to be of value because many bladder tumours are continuing to regress during this period of time. Progression of the tumour during or after radiotherapy can be detected either by CT scanning or ultrasonography.