title: Two-phase carcinogenesis in hamster buccal pouch.
abstract: A two-phase mechanism of chemical carcinogenesis in hamster buccal pouch has been demonstrated. Painting of buccal pouches three times weekly with a 0.1 percent solution of 7,12-dimethylbenz(a)anthracene (DMBA) in mineral oil for 10 weeks resulted in no visible tumors nor any microscopic evidence of dysplasia after the animals had been maintained for a 20 week period (Group 1 animals). Painting with 0.1 percent DMBA for 10 weeks, no treatment for a following 6 week period, and painting with 0.5 percent DMBA for a subsequent 4 weeks resulted in epidermoid carcinomas (Group 2 animals). Painting with 0.5 percent DMBA for 4 weeks in animals without prior treatment resulted in no tumors (Group 3 animals). It is postulated that the early treatment in Group 2 may serve for initiation and the later treatment for promotion.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000008:administration & dosage*; D000818:Animals; D001551:Benz(a)Anthracenes / Q000008:administration & dosage*; D006224:Cricetinae; D005260:Female; D008297:Male; D008647:Mesocricetus; D009061:Mouth Mucosa / Q000473:pathology; D009062:Mouth Neoplasms / Q000139:chemically induced* / Q000473:pathology; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000473:pathology; D013997:Time Factors
chemical_list: D001551:Benz(a)Anthracenes; D015127:9,10-Dimethyl-1,2-benzanthracene