Effects of subsequent antioxidant treatment on 7,12-dimethylbenz[a]anthracene-initiated carcinogenesis of the mammary gland, ear duct and forestomach in Sprague-Dawley rats.

The effects of the antioxidants tetramethyl-p-phenylenediamine (TMPD), propyl gallate (PG), quercetin (QC), 2-tert-butyl-4-methylphenol (TBMP), tert-butylhydroquinone (TBHQ), 3,3'-thiodipropionic acid (TDPA), guaiac gum (GG) and caffeic acid (CA) on 7,12-dimethylbenz[a]anthracene (DMBA)-initiated mammary gland, ear duct and forestomach carcinogenesis were examined in female Sprague--Dawley rats. Fifty-day-old rats were treated with 2.5 mg/100 g body wt of DMBA and, commencing 1 week thereafter, were given diets supplemented with 0.1% TMPD, 1.0% PG, 1.0% QC, 1% TBMP, 0.8% TBHQ, 1.0% TDPA, 1.0% GG or 0.5% CA for 51 weeks and then killed. Mammary tumor development was reduced by diet containing TMPD, PG, TBMP, TBHQ or GG, although this could be partly due to antioxidant treatment-associated decrease in body wt gain. The incidence of ear duct tumors was not affected by any of the antioxidant treatments. Development of forestomach tumors was enhanced in the group given DMBA followed by CA.