EFFECT OF NICOTINE ON 7,12-DIMETHYLBENZ[A]ANTHRACENE CARCINOGENESIS IN HAMSTER-CHEEK POUCH

We divided 40 male Syrian golden hamsters into four groups of 10 animals each, and we treated both cheek pouches of each hamster three times a week as follows: group 1, 50 μL of sesame oil; group 2, 50 μL of 6% nicotine in sesame oil; group 3, 50 μL of 1% 7, 12-dimethylbenz[a]anthracene (DMBA) in sesame oil; and group 4, 50 μL of 1% DMBA in 6% nicotine in sesame oil. Cheek pouches were examined clinically and histologically after 12 weeks of treatment. Hamsters treated with DMBA and nicotine showed significantly (P< .001) more tumors and a significantly (P< .05) greater-than-expected proportion of large tumors (≥ 3-mm diameter) than hamsters treated with DMBA alone. Histologically, there was a greater degree of dysplasia in lesions from the group receiving DMBA plus nicotine than in the DMBA only group. The results suggest that nicotine acts as a cofactor in DMBA tumorigenesis. [J Natl Cancer Inst 82:861-864, 1990] © 1990 Oxford University Press.