Different carcinogenic responses in a variety of organs, including the prostate, of five different rat strains given 3,2'-dimethyl-4-aminobiphenyl.

Tumorigenic response in the prostate of F344, ACI, Lewis, CD and Wistar rat strains to 3,2'-dimethyl-4-aminobiphenyl (DMAB) was examined in relation to development of other types of tumors. Rats of each strain aged 6 weeks were divided into two groups receiving DMAB s.c. at a dose of 50 mg/kg body wt once every other week for 10 times, with or without 1 week dietary ethynyl estradiol (EE) pretreatment. The experiment was terminated at week 60, carcinomas of the ventral prostate, all of microscopic size, being respectively found in 50, 17, 21, 15 and 0% of F344, ACI, Lewis, CD and Wistar strain animals treated with EE plus DMAB. The tumor yield correlated well with DMAB-DNA adduct formation. One invasive adenocarcinoma also developed in the periurethral part (occupying both of lateral and dorsal areas) of the prostate. The final survival rates were 46, 24, 65, 4 and 0% in F344, ACI, Lewis, CD and Wistar rats respectively. DMAB administration without EE pretreatment resulted in similar incidences of prostate tumors and mortalities. Tumors arose in greater than 14 different sites with strain dependency, lesions predominating in the skin/subcutis of ACI and F344, preputial gland of F344, urinary bladder of ACI, and mammary glands of CD rats respectively. Consideration of mortality and the relative incidence of prostate cancer and other types of tumors indicates the F344 rat strain to be the most appropriate for investigation of DMAB prostate carcinogenesis.