Inhaled cigarette smoke induces preneoplastic changes in rat tracheal epithelial cells

Rats were exposed 6 h/day, 5 days/week for 5 weeks to levels of cigarette smoke designed to deposit amounts of particulate per gram of lung similar to those experienced by a heavy smoker. Tracheal epithelial cells were isolated and examined in culture for the presence of preneoplastic variants. Two- to three-fold increases in the frequency of variants were observed in cells isolated from smoke-exposed animals compared to those from air-exposed controls. These results provide an estimate of the frequency of cigarette smoke-induced initiation events in respiratory epithelium that will be useful in further defining the role of cigarette smoke in the development of lung cancer.