Objective: We report the preliminary results of a phase I trial using indole-3-carbinol for the treatment of recurrent respiratory papillomatosis. Indole-3-carbinol is a chemical that is found in high concentrations in cruciferous vegetables and has been shown to alter the growth pattern of recurrent respiratory papillomatosis cell cultures and to be effective in an in vivo animal model of recurrent respiratory papillomatosis.

Methods: Eighteen patients were treated with oral indole-3-carbinol and had a minimum follow-up of 8 months and a mean follow-up of 14.6 months. All patients received indole-3-carbinol, and outcome measures included a change in papilloma growth rate and the need for surgery during treatment compared with before treatment. All patients had serial examinations with videoendoscopy to document papilloma location and growth rate.

Results: Thirty-three percent (6 of 18) of the study patients had a cessation of their papilloma growth and have not required surgery since the start of the study. Six patients have had reduced papilloma growth rate, and 6 (33%) patients have shown no clinical response to indole-3-carbinol. Indole-3-carbinol affects the ratio of hydroxylation of estradiol; changes in the ratios of urinary 2-hydroxylation and 16-hydroxylation of estradiol caused by indole-3-carbinol correlated well with clinical response. No major complications or changes in the children's growth curve were noted.

Conclusions: The preliminary results of treating recurrent respiratory papillomatosis with indole-3-carbinol holds promise. Longer follow-up of this patient group and a blinded, controlled trial are required. We conclude that indole-3-carbinol appears to be safe and well tolerated and may be an efficacious treatment for recurrent respiratory papillomatosis.