Tobacco Documents Online

I I I I I I I I I I I I I I I I I #89 AUTHOR: KOBAYASHI, NOBUTOSHI, DIETRICH HOFFMANN, AND ERNST L. WYNDER DATE: 1974 TITLE: A STUDY OF TOBACCO CARCINOGENSIS. XII. EPITHELIAL CHANGES INDUCED IN THE UPPER RESPIRATORY TRACTS OF SYRIAN GOLDEN HAMSTERS BY CIGARETTE SMOKE. CITATION: JOURNAL OF NATIONAL CANCER INSTITUTE, 53, No. 4, 1085-1087 (1974) STUDY DESIGN: Four groups (25 males each - 8-10 week old ) of Syrian golden hamsters were treated as follows: Group I was exposed to cigarette smoke after intratracheal instillation of 2 mg 7,12-dimethylbenz[a]anthracene (DMBA); Group II was exposed to cigarette smoke without the initial dose of DMBA; Group III received DMBA alone; and group IV (controls) received the vehicle alone. The central smoking chamber of the Hamburg II machine contained a diluted cigarette smoke with a smoke: air raito of 1:7. Each hamster breathed an aerosol that contained -.25-.3% CO (after 1 and 9 min of smoking), 0.75-1.55% C02, 68 mg TPMlliter, and 4.1 mg nicolineAiter. Nicotine and TPM values were 65-70% of theoretically expected values. Cigarettes was a popular U.S. brand (85mm) without filter tips purchased on open market in New York City in 1972-1973. Animals were killed when moribund or after 48 weeks of inhalation plus 4 weeks of observatlon. The larynx, pharynx, trachea, lungs, and head were dissected for histologic preparation. FINDINGSlRESULTS: Hamsters treated with both DMBA and smoke inhalation did not gain as much weight as the untreated controls, The difference was noted by the 3'd week of smoke exposure. Hamsters receiving DMBA alone or smoke alone gained less weight than the controls. In Group I, hyperplastic and neoplastic changes were most frequent in the laryngeal areas, especially the upper part covered by ciliated columnar epithelium. All laryngeal lesions were leukoplakic and were classified by histologic types as grades 1-4. Animals treated with DMBA and smoke exposure showed these epithelial changes earlier than animals treated with DMBA alone or smoke exposure along. No inflammatory cell infiltration into the lesions was observed. Neoplasms of other orangs and other lesions found were: squamous cell metaplasia of the nasal cavity was seen in 2 hamsters of group 144 weeks after inhalation began. One squamous cell papilloma in the oral cavity and 2 keratotic papillomas in the pharynx were observed in group I. Eleven hamsters in Group III had multiple keratinizing squamous cell papillomas of the forestomach. Two malignant melanomas of skin were found in 52-wee survivors in group Ill. The only changes recognized in the tracheobronchial tree and lung tissues in the experimental groups were 1 tracheal polyp in both groups I and Ill and 3 and 2 adenomatoid lesions in groups I and Ill, respectively. CONCLUSIONS: The results show that in hamsters pretreated with DMBA, cigarette smoke inhalation led to earlier and more extensive patholeglc changes in the upper respiratory system than in hamsters exposed to cigarette smoke alone 1