The Immediate Effects of Different Light Doses for Photodynamic Therapy of Endobronchial Tumors

Abstract

The immediate effects of different power densities and light dosages were determined on 77 sites of endobronchial tumors in 28 patients. All received 2 mg/kg of dihematoporphyrin ether 2 days prior to photodynamic therapy (PDT). Light (630 nm) was delivered with a tunable dye laser system through quartz fibers modified at the delivery end to disperse the light perpendicular to the axis of the fiber. The degree of obstruction, tumor consistency, edema, exudate, bleeding, amount of relief of obstruction, and complications were estimated before and at the end of treatment and toilet bronchoscopy. The authors found no difference in the effect of power densities of 400 mW/CF or 500 mW/CF when compared to the same total light dosage. However, 700 mW/CF produced coagulation of fibrin collection on fibers. By the end of the treatment, bleeding tumors did not bleed enough to prevent removal, although they were bleeding prior to PDT. The only complication during or after the increased light dosages was the formation of exudate. Hard tumors became soft and edematous by the end of the treatment permitting immediate removal of some tumors. At the time of discharge, the authors achieved greater than 50% reduction of obstruction, that is, complete and partial responses, in 64% of the patients with 200 J/CF, 71% with 300 J/CF, 82% with 400 J/CF, 77% with 500 J/CF, and 100% with 700 J/CF. Overall, they observed a 74% response, again, complete and partial response, at discharge.