Gold vapor laser versus tunable argon-dye laser for endobronchial photodynamic therapy

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Abstract
To compare the effectiveness of a gold vapor pulsed laser versus an argon dye continuous wave laser system in decreasing the amount of obstruction caused by endobronchial tumors when they are treated with photodynamic therapy (PDT). The percentage of endobronchial obstruction from tumors before and at the end of PDT, and before and at the end of toilet bronchoscopy of 96 sites treated with light generated by a Spectra Physics tunable argon dye system were compared to those of 17 sites treated with light generated by a gold vapor laser. All patients were injected intravenously with 60 mg of dihematoporphyrin ethers per square meter of body surface. All treatments were done with a power density of 500 mW/CF and a light dose of 400 J/CF delivered from cylinder diffusing fibers. Paired Student's t-tests and Wilcoxon signed ranks tests showed significant decreases in the percentage of endobronchial obstruction due to PDT regardless of the laser used. Unpaired Student's t-tests and Mann-Whitney U statistical comparisons showed no significant difference between the two lasers in the percentage decrease at PDT, percentage increase from exudate seen at toilet bronchoscopy, nor the percentage decrease at the end of the toilet bronchoscopy from that before PDT. We found no statistically significant difference in the decrease in the amount of endobronchial tumor obstruction obtained when the light for treatment was generated by a pulsed gold vapor or a continuous wave argon dye laser system.