Progress of gastric cancer etiology: N-nitrosamides 1999s

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.