AffiliationCancer Institute, Chinese Academy of Medical Sciences, Beijing, People's Republic of China.
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AbstractStudies on the relevance of the N-nitrosamines to esophageal cancer in China are reviewed. Esophageal cancer is a complex and multifactorial problem. Although a causal association between nitrosamines exposure and esophageal cancer in China has not yet been rigorously established, exposure of Lin-Xian subjects to nitrosamines either directly or as a result of their in vivo formation has been detected in our study. Several N-nitrosamines (NDMA, NDEA, NMBzA, NPyr, NPip, and NSAR) in gastric juice collected from Lin-Xian inhabitants have been detected. A correlation was found between the lesions of esophageal epithelium and the amount of nitrosamines present. In addition, the amounts of N-nitrosamino acids (N-nitrosoproline, N-nitrosothiazolidine 4-carboxylic acid, NSAR, and nitrates) excreted in 24-hr urine of subjects in Lin-Xian were significantly higher than those in Fan-Xian, indicating a higher exposure to N-nitroso compound and their precursors of the inhabitants in the high-risk area. The effect of nitrosamines on human esophagus has been investigated at the cellular levels. The amounts of O6-MedG in DNA of esophageal or stomach mucosa of patients from Lin-Xian were higher than that from Europe (Lyon and Essen). The presence of O6-MedG in the human fetal esophagus cultured with NMBzA was also detected. These findings indicate that the elevated levels of O6-MedG in esophageal DNA could be the result of a recent exposure to N-nitroso compounds or a genetically determined reduced cellular capacity for repair of O6-MedG from DNA. The hyperplasia was induced in the esophagus of human fetus that cultured with NMBzA for 2 weeks to 2 months. The intervention studies of esophageal cancer in Lin-Xian have been pursued. Intake of moderate doses of ascorbic acids by Lin-Xian subjects effectively reduced the urinary levels of N-nitrosamino acids to those found in un-dosed subjects in the low-risk area. If N-nitroso compounds are formed in vivo and are among the causative factors of esophageal cancer in Lin-Xian, ascorbic acid appears to be effective in lowering the body burden of these carcinogenic compounds. Thus, the plan of chemoprevention is carried out in Lin-Xian.
CitationRelevance of N-nitrosamines to esophageal cancer in China. 1986, 4:51-8 J Cell Physiol Suppl
JournalJournal of Cellular Physiology. Supplement
- Urinary excretion of N-nitrosamino acids and nitrate by inhabitants of high- and low-risk areas for esophageal cancer in Northern China: endogenous formation of nitrosoproline and its inhibition by vitamin C.
- Authors: Lu SH, Ohshima H, Fu HM, Tian Y, Li FM, Blettner M, Wahrendorf J, Bartsch H
- Issue date: 1986 Mar
- [N-nitrosamines in gastric juice of subjects from high incidence area of esophageal cancer].
- Authors: Lu SX
- Issue date: 1988 Sep
- Determination of N-nitrosamines in gastric juice and urine and a comparison of endogenous formation of N-nitrosoproline and its inhibition in subjects from high- and low-risk areas for oesophageal cancer.
- Authors: Lu SH, Yang WX, Guo LP, Li FM, Wang GJ, Zhang JS, Li PZ
- Issue date: 1987
- [Exposure level of N-nitrosamines in the gastric juice and its inhibition by vitamin C in high risk areas of esophageal cancer].
- Authors: Yang WX
- Issue date: 1992 Nov
- Relevance of N-nitrosamines to oesophageal cancer in China.
- Authors: Lu SH, Chui SX, Yang WX, Hu XN, Guo LP, Li FM
- Issue date: 1991