胃癌高低发区居民空腹胃液中N—亚硝酰胺总含量的比较

Ｎ－亚硝酰胺（ＮＡＤ）为高度可疑的人胃癌病因,但缺乏直接的流行病学证据。本研究探讨了ＮＡＤ暴露与人胃癌流行的相关性。方法利用胃液痕量ＮＡＤ总量分析和胃镜活检等技术,对胃癌高发区山东省临朐县和低发区苍山县３５～６８岁居民空腹胃液中ＮＡＤ暴露水平进行比较。结果（１）高发区样品ＮＡＤ的阳性率（ｎ＝１７６,４０．９％）高于低发区（ｎ＝９９,３０．３％）,经标化后有统计学意义（ｐ＝０．０３２４）。（２）在高发区仅４８％胃液样品的ｐＨ≤３,而在低发区则高达８４％（ｐ＜０．００１）;在ｐＨ≤３的样品中,ＮＡＤ的阳性率也是高发区高于低发区（４６．２％比２７．４％,ｐ＜０．０１）;在低发区样品中,ｐＨ值高者ＮＡＤ的阳性率高于ｐＨ值低者,在高发区则无此现象。（３）慢性缩性胃炎（ＣＡＧ）和ＣＡＧ伴异型增生者,胃液ＮＡＤ的阳性率高于胃粘膜正常和浅表性胃炎者。结论本研究揭示,ＮＡＤ的暴露与胃癌的流行可能存在正相关关系,ＣＡＧ和异型增生与ＮＡＤ致胃癌过程关系密切。

Comparison of total N-nitrosamides in fasting gastric juice from subjects in high and low risk areas for gastric cancer

OBJECTIVE: The status of human exposure to N-nitrosamides (NAD) is almost unknown, although they are probably carcinogenic to human stomach. This study is to elucidate the relationship between NAD exposure and causes of gastric carcinomas (GC). METHODS: The total amount of natural NAD was detected with a photohydrolysis-TEA method (184 nmole/l, detection limit) in fasting gastric juice samples from subjects aged 35-68 by fibroendoscope both in a high and low risk area for GC with the same geographical and socioeconomic conditions in Shangdon Province, China. RESULTS: A) More NAD-positive samples in the high risk area (Linqu County, n = 176) were observed than in the low risk area (Chongshan County, n = 99), the difference was significantly after age-adjustment (40.9% vs. 30.3%, P = 0.0324). B)84% of samples was pH < or = 3 in Chongshan, whereas only 48% in Linqu (P < 0.001). In the acidic samples more NAD-positive ones in Linqu were found than in Chongshan (46.2% vs 27.4%, P < 0.01). NAD-positive rate was higher in samples with pH > or = 5 than those with pH < or = 3 only in the low but not in the high risk area. C)NAD-positive rate was also higher in samples from subjects with chronic atrophic gastritis (CAG) with or without dysplasia than those from normal subjects and from those with superficial gastritis or CAG with intestinal metaplasia both in the high and low risk areas. CONCLUSION: The results suggest that human endogenous exposure to NAD in the high risk area for GC be higher than that in the low risk area; CAG and dysplasia may play a role in human gastric carcinogenesis by N-nitrosamides.