Correlation between precancerous bronchial metaplasia and cigarette consumption, and preliminary results of retinoid treatment.

Vitamin A and its derivatives, so-called retinoids, can prevent squamous metaplasia induced not only by vitamin A deficiency but also by carcinogenic hydrocarbons. An aromatic retinoid, such as ET1, has been shown to prevent chemically induced papillomas in mice and to amplify certain immunologic reactions. Heavy smokers, 106 volunteers, were submitted to fibrobronchoscopy with bronchial biopsies. An index of metaplasia (IM) was calculated on the basis of microscopical examination of a total of 9,633 sections of 1,010 biopsies. Despite the subjectivity of the estimates of cigarette consumption, this was significantly (P less than 0.02) and positively correlated to the IM. Eighty-five percent of the women had a low IM as compared to only 42% of the men (P less than 0.01), although there was no significant difference in the reported cigarette consumption. Fifty-two subjects had an IM greater than 15% and were given 25 mg ET1 orally daily for 6 months. The bronchoscopy was repeated in 30 patients following completion of the 6-month treatment. The IM was significantly (P less than 0.01) reduced after treatment.