Regression of experimental cancer by oral administration of combined alpha-tocopherol and beta-carotene.

alpha-Tocopherol (vitamin E) and beta-carotene have been shown to be capable of regressing established epidermoid carcinomas of hamster buccal pouch when injected locally into the tumor site. Neither has yet been shown to be effective in regressing cancer when administered by oral route. However, a combination of both alpha-tocopherol and beta-carotene was shown to be effective in regressing epidermoid carcinomas of hamster buccal pouch when the mixture was administered orally in vegetable oil. The epidermoid carcinomas were induced in the right buccal pouch of 100 Syrian hamsters by painting three times weekly for 14 weeks with a 0.5% solution of 7,12-dimethylbenz[a]anthracene in mineral oil. The animals were then divided into five equal groups of 20 animals. Group 1 animals received no further treatment and represented tumor controls. Group 2 animals received 200 micrograms beta-carotene and 200 micrograms dl-alpha-tocopherol acid succinate combined in 0.2 ml vegetable oil. Animals received the mixture daily by mouth using a 1-ml syringe. Groups 3 and 4 received beta-carotene and alpha-tocopherol individually in double amounts (400 micrograms in 0.2 ml vegetable oil). Group 5 animals received only the vegetable oil (0.2 ml daily) and were controls for vehicle. The animals in Groups 1, 3, 4, and 5 were killed after 22 weeks because the tumors were extensive, large, and necrotic and the animals were weak and cachectic. After 22 weeks, the tumors in Group 2 animals were small in 15 out of 20 animals. The tumors were reduced in size compared with tumor burden at 14 weeks, the point at which the beta-carotene/alpha-tocopherol was started.