N-(4-hydroxyphenyl)all-trans-retinamide (4-HPR) high dose effect on DMBA-induced hamster oral cancer: a histomorphometric evaluation.

N-(4-hydroxyphenyl)all-trans-retinamide (4-HPR) has shown cancer chemoprevention activity in many experimental and clinical situations. The purpose of this research is to evaluate the in vivo efficacy of 4-HPR in preventing 7,12-dimethylbenz(alpha)antracene (DMBA)-induced oral carcinogenesis and to study histomorphometric changes. 76 Syrian hamsters were separated into four groups: group 1, untreated controls (16 animals); group 2, 4-HPR controls (16 animals); group 3, DMBA-treated animals (28); group 4, animals treated with DMBA and 4-HPR (16).