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

Tumorigemc response in the prostate of F344, ACI, Lewis, CDand Wistar rat strains to 3,2'-dimethyl-4-amtnobiphenyl (DMAB)was examined in relation to development of other types of tumors.Rats of each strain aged 6 weeks were divided into two groupsreceiving DMAB S.C. at a dose of 50 mg/kg body wt once everyother week for 10 times, with or without 1 week dietary ethynylestradiol (EE) pretreatment. The experiment was terminated atweek 60, carcinomas of the ventral prostate, all of microscopicsize, being respectively found in 50, 17, 21, 15 and 0% of F344,ACI, Lewis, CD and Wistar strain animals treated with EE plusDMAB. The tumor yield correlated well with DMAB–DNA adductfor mation. One invasive adenocarcinoma also developed in theperlurethral part (occupying both of lateral and dorsal areas)of the prostate. The final survival rates were 46, 24, 65, 4and 0% in F344, ACI, Lewis, CD and Wistar rats respec tively.DMAB administration without EE pretreatment resulted in similarincidences of prostate tumors and mor talities. Tumors arosein >14 dIfferent sites with strain dependency, lesions predominatingin 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 prostatecancer and other types of tumors indicates the F344 rat strainto be the most appropriate for investigation of DMAB prostatecarcinogenesis.