Relationship of tobacco smoking, CYP1A1, GSTM1 gene polymorphism and esophageal cancer in Xi’an

Table 1 Comparability of age and gender in cases and controls

Factor	Case	Control	χ2	P
Age(year)
< 50	28	16
50-	38	44
≥ 60	61	41	4.73	0.094
Gender
Male	97	78
Female	30	23	0.02	0.80

Table 2 Distributions of smoking, GSTM1 deletion and CYP1A1 genotypes

Factors	Case	Control	OR	OR95%CI	χ2	P
Smoking Yes	69	38	1.97	1.12-3.48	6.28	0.012
No	58	63
GSTM1
Deletion	74	44	1.81	1.03-3.18	4.85	0.028
Exist	53	57
CYP1A1
Ile/Ile	25	31	1.00		1.00
Ile/Val	58	48	1.50	0.74-3.03	1.48	0.22
Val/Val	44	22	2.48	1.12-5.54	5.93	0.015

Table 3 Interaction of smoking and GSTM1 deletion genotype.

Smoking	GSTM1 deletion	Case	Control	OR	OR95%CI	χ2	P
No	No	25	37	1.00
Yes	No	28	20	2.07	0.90-4.80	3.48	0.062
No	Yes	33	26	1.88	0.86-4.13	2.93	0.087
Yes	Yes	41	18	3.37	1.49-7.69	10.29	0.0013

SIA = 3.37/(1.88+2.07-1.00) = 1.14

Table 4 Interaction of tobacco smoking and CYP1A1 Val/Val genotype

Smoking	CYP1A1(Val/Val)	Case	Control	OR	OR95%CI	χ2	P
No	No	36	47	1.00
Yes	No	47	32	1.92	0.98-3.76	4.18	0.04
No	Yes	22	16	1.80	0.77-4.20	2.18	0.14
Yes	Yes	22	6	4.79	1.62-14.83	10.30	0.0013

SIM = 4.79 / (1.92 × 1.80) = 1.39

Table 5 Interaction of CYP1A1 mutation genotypes(Val/Val, Ile/Val) and GSTM1 deletion genotype

GSTM1 deletion	CYP1A1 mutation	Case	Control	OR	OR95%CI	χ2	P
No	No	10	20	1.00
No	Yes	43	37	2.32	0.89-6.14	3.61	0.057
Yes	No	15	11	2.73	0.81-9.42	3.28	0.070
Yes	Yes	59	33	3.58	1.39-9.38	8.66	0.0033

Table 6 Analysis of CYP1A1 genotypes in cases and controls with Stratified GSTM1 deletion

CYP1A1 genotype	GSTM1 deletion		existing GSTM1
	Case	Control	Case	Control
Ile/Ile	15	11	10	20
Ile/Val	35	19	23	29
Val/Val	24	14	20	8
χ2	0.39		9.04
P	0.83		0.011