Induction of stomach cancer by the chronic action of arsenic

: Out of 18 albino rats which survived 17-24 months after implantation in a partially isolated glandular stomach compartment of a perforated polyethylene capsule containing 8 mg arsenic trioxide in a fat-wax mixture as vehicle, two developed muconodular adenocarcinoma and one--mucoid cystic adenocarcinoma in that gastric compartment; metastasis into the liver was detected in one animal. No malignant tumors were found in 9 rats with the same post-surgical survival time after implantation of a control capsule containing the same mixture without arsenic. Since spontaneous gastric cancers practically fail to appear in laboratory rats, nor have they ever been reported by other authors after control capsule implantation but developed in some rats after implantation of a carcinogen-containing one, the results of the present investigation may be interpreted as an experimental proof of the carcinogenicity of arsenic which was previously assumed on epidemiologic evidence.