title: A family of epidermoid lung cancer models.
abstract: A method of sustained release implantation has been developed whereby Silastic cylinders, impregnated with benzo[alpha]pyrene (BP) or methylcholanthrene (MCA) each at 2% (low dose) and 10% (high dose) concentrations, were inserted into the bronchus intermedius of hamsters. High-dose BP and MCA, and low-dose MCA had first-order exponential release rates: the half-time of release was 40 days for high-dose BP, 30 days for high-dose MCA, and 165 days for low-dose MCA. Release rate of low-dose BP was a second-order function: half-time of release was 40 days. Atypical squamous metaplasia was noted by 4 weeks in more than 65% of hamsters after insertion of each high-dose carcinogen but in less than 30% with the low-dose carcinogens. Carcinoma in situ was noted approximately 8 weeks after high-dose BP and 19 weeks after low-dose BP. At about 15 to 17 weeks after a high-dose carcinogen, 64% of animals had invasive epidermoid cancer, whereas after a low-dose carcinogen, only 21% did. After 25 weeks of exposure to a high-dose carcinogen, more than 85% of hamsters had invasive epidermoid cancer; up to 52 weeks were required for invasive epidermoid cancer to develop in 30% after a low-dose carcinogen. Measured by image analysis, nuclear deoxyribonucleic acid content of cells with severe atypical squamous metaplasia was greater than tetraploid (mean +/- standard deviation [SD], 3.77 +/- 1.4), whereas cells with invasive epidermoid cancer were suprahexaploid (mean +/- SD, 6.48 +/- 3.6). These differences are significant (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000008:administration & dosage*; D001984:Bronchial Neoplasms / Q000139:chemically induced / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced* / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D006224:Cricetinae; D004247:DNA / Q000378:metabolism; D004195:Disease Models, Animal; D004343:Drug Implants; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000473:pathology; D008647:Mesocricetus; D008748:Methylcholanthrene / Q000008:administration & dosage*; D013997:Time Factors
chemical_list: D004343:Drug Implants; D001564:Benzo(a)pyrene; D008748:Methylcholanthrene; D004247:DNA