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

40 voluntary heavy smokers (over 15 packets-years) were selected for and have completed a six months 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 10 sites of the bronchial tree. Each biopsy was cut into 10 sections and an IM was calculated: (Formula: see text). Etretinate, a retinoid derivative, was given orally at the daily dose of 25 mg, at the end of which they 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 4 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.