Interaction of methylenetetrahydrofolate reductase C677T, cytochrome P4502E1 polymorphism and environment factors in esophageal cancer in Kazakh population

Table 1 Environmental risk factors for EC in Kazakh population

Environmental risk factors	Case n (%)	Control, n (%)	P1	OR (95% CI)1
Consumption of green vegetables
Frequently	42 (35.00)	126 (52.50)	-	1.00
Occasionally	45 (37.50)	90 (37.50)	0.106	2.54 (0.91-2.59)
Less	33 (27.50)	24 (10.00)	0.000	4.66 (2.33-9.30)
Consumption of fresh fruits
Frequently	13 (10.83)	1 (29.58)	-	1.00
Occasionally	71 (59.17)	145 (60.42)	0.003	2.79 (1.43-5.43)
Less	36 (30.00)	24 (10.00)	0.000	9.03 (3.90-20.89)
Smoking status
Never	50 (41.67)	100 (41.67)	-	1.00
Former	29 (24.17)	42 (17.50)	0.309	1.39 (0.74-2.62)
Current	41 (34.16)	98 (40.83)	0.509	0.83 (0.47-1.45)
Alcohol drinking frequency
Never	50 (41.67)	152 (63.33)	-	1.00
1-2 times/wk	34 (28.33)	61 (25.42)	0.002	3.28 (1.54-7.01)
3-4 times/wk	29 (24.17)	21 (8.75)	0.000	7.31 (3.14-17.03)
≥ 5 times/wk	7 (5.83)	6 (2.50)	0.005	6.00 (1.71-21.02)
Drinking water source
Safe water	43 (35.83)	163 (67.92)	-	1.00
Shallow well water	20 (16.67)	25 (10.41)	0.002	2.88 (1.47-5.66)
River water	57 (47.50)	52 (21.67)	0.000	4.40 (2.55-7.60)

¹ORs, 95% CIs and P values were calculated in a conditional logistic regression model.