The modifying roles of age, sex, and strain of mice on the incidence, multiplicity, and spectrum of
tumors induced by
benzo(a)pyrene have been investigated. The first-generation (F1) hybrids of C57BL/6J X C3HeB/FeJ and C3HEB/Fej X A/J mice of both sexes were given single i.p.
injections (75 or 150 mug/g) of
benzo(a)pyrene at 1, 15, or 42 days of age. Experimental animals were allowed to live their life-spans, while animals in control groups were killed at 52, 90, 142, or 170 weeks of age. Animals treated with
benzo(a)pyrene died, in general, by the 100th week of age due to development of liver, lung, stomach and lymphoreticular
tumors. Few of the control animals died during that same observational period. The age of mice at the time of exposure to the
carcinogen modified development of
tumors at all the sites. The sex of animals influenced the development of liver and lymphoreticular
tumors. The C3HeB/FeJ X A/J F1 hybrids developed lung
tumors more readily than did the C57BL/6J X C3HeB/FeJ F1 mice, which had significantly more liver
tumors and
neoplasms of the lymphoreticular system than the former strain. No strain difference was observed in regard to
tumors at other sites. Higher doses of
benzo(a)pyrene were more effective in inducing lung, liver, and stomach
tumors. In addition, 5 cases of pancreatic ductal
adenoma and
adenocarcinoma were observed in
carcinogen-treated mice.