[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.