Progress of gastric cancer etiology: N-nitrosamides 1999s

Table 1 Comparison of formation of NMU at various doses of NaNO₂ in gastric lumen of pig model in vivo and control experiments in vitro[9,22]

Formation of NMU
Amount of NaNO2(μmol)	Concentration (μmol/L)		Total amount (μmole)
	in vivo	in vivo	in vivo	in vivo
3480	25.40	29.20	4.27	1.75
870	7.97	6.48	1.91	0.38
220	ND	2.77	ND	0.17

ND, below detection limit; the value was the average of two independent experiments.

Table 2 Status of gastric juice samples from four human volunteers and formation of NMU 30 min after taking 40 mL of diluted fish sauce and 500 μmol of nitrite[9]

Sample’s origin	Total volume of sample (mL)	pH of sample	Total amount of NMU detected in gastric lumen (nmol)
Male A	24	5.0	4
Male B	110	3.0	85
Female A	50	2.0	100
Female B	50	2.0	22

Table 3 Relationship between presence of total N-nitrosamides in gastric juice samples from subjects with pathological changes in gastric mucosa

Gastric mucosal status	Positive rate of total N-nitrosamides in gastric juice samples (%)**
	High risk areas		Low risk area
	Putian[13]	Linqu[28]	Cangshan[28]
*N and CSG	2/12 (16.7)	1/4 (25.0)	4/23 (17.4)
CAG	10/14 (71.4)b	38/76 (50.0)c	18/56 (32.1)
CAG and IM	12/13 (92.3)	17/56 (28.8)e	0/4 (0.0)
CAG and DYS 12/13 (92.3)		18/44 (40.9)	5/10 (50.0)

*N, normal mucosa; CSG, chronic superficial gastritis; CAG, chronic at rophic gastritis; IM, intestinal metaplasia; DYS, dysplasia;

^**sample was classified as N-nitrosamides-positive when more than 184 nmol/L (de tection limit) of the chemicals was detected;

^bSignificantly different fr om N and CSG with P < 0.01;

^cSignificantly different from low risk a rea with P < 0.05;

^eSignificantly different from CAG with P < 0.05.

Table 4 Presence of total N-nitrosamides (NAD) in gastric juice samples (GJ) from low and high risk areas for stomach cancer

	High risk area (Linqu)	Low risk area (Chongshan)	P-value
No. of GJ samples	176	99
Proportion, pH ≤ 3	48.0%	84.0%	< 0.01
pH ≥ 5	45.3%	13.5%	< 0.01
Positive rate, all	40.9%	30.3%	= 0.03*
GJ, pH ≤ 3	46.2%	27.4%	< 0.01
GJ, pH ≥ 5	43.3%	53.9%
Conc. (μmol/L)	0.91	0.73

^*after age-adjustment.