Regression of bronchial epidermoid metaplasia in heavy smokers with etretinate treatment.

Forty heavy-smoker (over 15 packets per year) volunteers were selected for and have completed a 6-month etretinate treatment on the basis of an index of metaplasia (IM) greater than 15% determined according to the following procedure: bronchoscopy with systematic biopsies in ten sites of the bronchial tree. Each biopsy was cut into ten sections and an IM was calculated: IM = number of sections with epidermoid metaplasia/number of sections examined X 100. Etretinate, a retinoid derivative, was given orally at the daily dose of 25 mg, at the end of which patients underwent a second fibroscopy protocol. A highly significant reduction of IM (P = 10(-5)) was observed after 6 months of treatment for those of the patients who maintained their smoking habits during treatment. Besides, the four patients who stopped smoking while under treatment and are excluded from the statistical analysis all had a complete regression of metaplasia at the second fibroscopy. No morbidity was due to etretinate or fibroscopy. Etretinate significantly reduces potentially precancerous bronchial epidermoid metaplasia in heavy smokers. Its association with smoking arrest may induce a rapid restoration of bronchial epithelium to normal.