The therapeutic effect of an aromatic retinoid (RO-109359) on hamster buccal pouch carcinomas.

Forty male hamsters were divided into three groups. Group 1 (16 animals) received topical applications with a 0.5% solution of DMBA in liquid paraffin on the right buccal pouch for 16 weeks. Group 2 (16 animals) received DMBA for 16 weeks, plus the retinoid RO-109359 three times during the 17th week in doses of 200 mg/kg. Group 3 (8 animals) remained untreated for 16 weeks and, during the 17th week, received the retinoid as in group 2. After administration of the retinoid, a marked regression in the size of the carcinomas of the right pouch in group 2 animals was observed clinically. Histologically, these tumors consisted mostly of large necrotic areas and showed an excessive keratin loss. Although the hypervitaminosis A symptoms could not be avoided, the findings suggest that high doses have a therapeutic effect on hamster buccal pouch carcinomas.