Variable light-dose effect on photodynamic therapy for laryngeal papillomas.

OBJECTIVE: We investigated photodynamic therapy (PDT) as an alternative treatment modality for recurrent respiratory papillomatosis. To optimize the effect of PDT, the light dose in this study was increased from 50 to 80 J/cm2. The clinical effect of these two light doses will be discussed and compared.

DESIGN: Each patient's response was based on the growth rate of their papilloma before and after PDT. Disease response following 50 J/cm2 was compared with that after 80 J/cm2. The two study groups were also compared with a control group.

SETTING: Each patient received the dihematoporphyrin ether as an outpatient and underwent direct laryngoscopy and PDT at our institution.

PATIENTS: Twenty-eight patients (16 male and 12 female) with moderate to severe laryngeal disease and an age range of 18 months to 80 years were treated with a light dose of 80 J/cm2, 11 of those had been previously treated with 50 J/cm2. Seven patients had undergone photoactivation to the trachea.

INTERVENTION: Twenty-four hours prior to photoactivation, patients received 2.5 mg/kg of dihematoporphyrin ether intravenously. Photodynamic therapy was given using an argon pump dye laser system.

MAIN OUTCOME MEASURE: Reduction in disease severity greater than that achieved with 50 J/cm2.

RESULTS: For patients treated initially with 80 J/cm2, the mean rate of papilloma growth decreased by approximately 50%, the same response seen with 50 J/cm2 of treatment. No additional benefit was found for those patients initially activated at 50 J/cm2 and then re-treated at 80 J/cm2.

CONCLUSION: Although PDT has a beneficial effect on laryngeal papilloma growth rate, no significant change in response was obtained by increasing the light dose from 50 to 80 J/cm2.