Contribution PRE-OPERATIVE IRRADIATION OF T 3 XARCINOMA IN BILHARZIAL BLADDER : A COMPARISON BETWEEN HYPERFRACTIONATION AND CONVENTIONAL FRACTIONATIONt

The present report deals with a prospective randomized study investiiting the valw of pre-operative telecobalt hradiation in the management of Tfcarcinoma in Bilharxlal bladder. A total pre-operatlve dose of 4tNXlrad was split into 2 equal courses with a gap of 1 week. Two dose-thne reghnens were compared: split-course conventional fractionation, 200 rad/day (SC) and hyperfractionatlon (IIF). In the latter, the dally dose amounted to 1OOfl rod and was divided into 17 hourly acute fractions, 60 rad each. The SC and HF regimens produced equivalent local tissue reactions. Hyperfractlonatlon, however, was associated with a somewhat higher incidence of radiation sickness. Both regimens resulted in an increase of the 2-year disease-free survival rate from 19 * 10% (3/16) to 53 ? 9% (17/32) without added surgical haxard; both HF and SC appeared to be equally effective. An appreciable post-irradiation tumor shrinkage was noted in the majority of patients; this is consistent with a rapld tumor cell turnover rate. Moreover the likelihood of long term local tumor control seemed to be greater in the more rapidly shrinking tumors. This is proposed to be linked to a more extensive reoxygenatlon process. No correlation was obtained between the quantitative scoring of the cytohistologiil radiation effect and the outcome of treatment.