Photoradiation therapy of bladder tumors

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