Regression of experimental oral carcinomas by local injection of β‐carotene and canthaxanthin

Abstract

Regression of 7,12‐dimethylbenz[a]anthracene (DMBA)‐induced epidermoid carcinomas of hamster buccal pouch was accomplished by local injections of ß‐carotene and canthaxanthin. One‐hundred male hamsters (2–3 months old) were divided into five groups of 20 animals. All animals had the right buccal pouches painted three times weekly for 14 weeks with a 0.5% solution of DMBA in mineral oil, at which time all animals exhibited gross tumors of variable size and number. Group 1 animals were then injected locally into the right buccal pouch twice weekly for 4 weeks with 250 μg‐carotene in 0.1 ml minimal essential medium (MEM) per injection. Group 2 animals were similarly injected with 250 μg canthaxanthin in 0.1 ml MEM. Group 3 animals were similarly injected with 250 μg 13‐cis‐retinoic acid in 0.1 ml MEM. Group 4 animals were injected only with MEM; Group 5 animals were untreated controls. Animals were killed in a carbon dioxide chamber, and buccal pouches were photographed. Tumors were counted and measured. Tumor burden in each group was compared, and statistical significance between groups was recorded. ß‐Carotene was more effective than canthaxanthin in tumor regression. 13‐cis‐Retinoic acid had no effect in this system.