Chemoprevention of oral cancer by black raspberries

Abstract

Oral cavity cancers represent 2.5% of the cancers that occur in the United States and are ranked sixth worldwide. Since current therapeutic protocols are relatively ineffective, alternative strategies for prevention need to be developed and tested in appropriate animal models. In the study reported herein, the hamster cheek pouch (HCP) was used to evaluate the ability of black raspberries to inhibit oral cavity tumors. Male Syrian Golden hamsters, 3-4 weeks of age, were fed 5% and 10% lyophilized black raspberries (LBR) in the diet for two weeks prior to treatment with 0.2% 7,12-dimethylbenz(a) anthracene in dimethylsulfoxide and for 10 weeks thereafter. HCPs were painted 3X/week for eight weeks. The animals were sacrificed 12-13 weeks from the beginning of DMBA treatment and the number and volume of tumors (mm3) determined. There was a significant difference (p = 0.02) in the number of tumors between the 5% LBR and control groups (27 tumors/14 animals and 48 tumors/15 animals, respectively) and an intermediate number of tumors in the 10% berry-treated animals (39 tumors/15 animals). These experiments support previous studies from our laboratories showing the chemopreventive activity of black raspberries and show, for the first time, that dietary black raspberries will inhibit tumor formation in the oral cavity.