Photoradiation therapy of bladder tumours.

Photoradiation therapy (PRT), in which hematoporphyrin derivative (HpD) is activated by an argon-dye laser, was used on 46 superficial bladder tumours in 9 patients. It was suggested that there is little or no thermal cell killing effect of laser irradiation from study of the heating effect of the beam intensity. A fluorospectrophotometric study of biopsies from these tumorus and normal mucosa revealed preferential HpD localization in the malignant tissues. In tumours less than 1 cm diameter treated with 150 mwatts per cm2 for 5 minutes there were 2 CR and 5 NC, whereas with 200 mwatts per cm2 or more for the same time there were 15 CR and 5 PR. Concerning the accumulated energy intensity of the light, in tumours 1 cm in size or less, treatment with 100-250 joules per cm2 obtained CR in 5 of 6 tumours. From these results, it was suggested that the light intensity should be 300 mwatts per cm2 for 5-10 minutes or more and the total light dose should be 100 joules per cm2 or more in tumours up to 2 cm in size. There was no CR in tumours more than 2 cm in size. No early side effects were seen from the administration of HpD. Sensitivity to sunlight was seen in 4 cases.