Site specific cancer induction by intra -esophageal cotton node retention and carcinogen laden drinking water

Abstract

Objective: To reveal the relationship between the restriction of esophagus and the esophageal carcinogenesis. Methods: Male Wistar rats weighing 200±20g (N=50) observed as experimental animals. Using carcinogen N-ethyl-N-butyl-nitrosamine (EBN), or N-nitrosomethyl-N-propylamine (MPN), esophageal carcinogenesis was induced. In some rats, a cotton node was detained in the thoracic segment of the esophageal lumen to make artificial restriction. The rats were divided into 6 groups. Group EC or MC were those treated with the artificial restriction and EBN, or MPN. Group E, M or C included those treated only with EBN, MPN, or cotton node. Group U was untreated control. The rats were sacrificed, and the esophagus from the 6 groups of rats were compared. Results: On naked eye examination, the esophageal lesion was the most in EC group, followed by MC group. About 70% of the lesions were within 3mm from the thread node. The E or M group only had a few lesions. There was no observable lesion in the C and U groups. Histological examination found that the hyperplasia, hyperkeratosis, papilloma, and dysplasia were significantly more in EC and MC groups than E and M groups. Severe dysplasia and carcinomain situ were only noticed in the EC and MC groups. Conclusion: It is suggested that the artificial restriction promotes the esophageal carcinogenesis. The effect is related with increased contact with carcinogen and injury at the area of the restriction.