Genetic susceptibility and environmental factors of esophageal cancer in Xi’an

Table 1 Risk factors for esophageal cancer

Risk factors		Case	Control	OR	OR95%CI	χ2	P
Tobacco smoking	Yes	70	38	2.04	1.15-3.60	6.88	0.009
	No	59	63
Alcohol drinking	Yes	50	16	3.45	1.74-6.91	15.08	0.000
	No	77	85
FHEC	Yes	27	8	3.14	1.28-7.94	7.67	0.006
	No	100	93
GSTM1	Deletion	74	44	1.81	1.03-3.18	4.85	0.028
	Existed	53	57
CYP1A1	Ile/Ile	21	31	1.00
	Ile/Val	56	48	1.72	0.83-3.58	2.50	0.114
	Val/Val	50	22	3.35	1.49-7.61	10.33	0.001

FHEC: family history of esophageal cancer.

Table 2 Synergic interactions of tobacco smoking and GSTM1 deletion genotype

Tobacco smoking	GSTM1 deletion	Case	Control	OR	OR95%CI	χ2	P
No	No	24	37	1.00
No	Yes	33	26	2.96	0.89-4.33	3.28	0.07
Yes	No	29	20	2.24	0.97-5.19	4.24	0.04
Yes	Yes	41	18	3.51	1.55-8.05	10.89	0.001

SIA = 3.51 / (2.24 + 1.96 - 1.00) = 1.10. SIA: Synergic index of addition.

Table 3 Synergic interactions of alcohol drinking and GSTM1 deletion genotype

Alcohol drinking	GSTM1 deletion	Case	Control	OR	OR95%CI	χ2	P
No	No	35	48
No	Yes	42	37	1.56	0.80-3.04	1.95	0.16
Yes	No	18	9	2.74	1.01-7.55	4.85	0.03
Yes	Yes	32	7	6.27	2.30-17.72	16.91	0.00

SIM = 6.27 / (1.56 × 2.74) = 1.47 SIM: Synergic index of multiplication.

Table 4 Synergic interaction of GSTM1 deletion genotype and family history of esophageal cancer

ECFH	GSTM1deletion	Case	Control	OR	OR95%CI	χ2	P
No	No	44	53	1.00
No	Yes	56	40	1.69	0.92-3.11	3.24	0.07
Yes	No	9	4	2.71	0.69-12.76	2.59	0.11
Yes	Yes	18	4	5.42	1.60-23.34	9.47	0.00

SIM = 5.42 / (1.69 × 2.71) = 1.18.

Table 5 Interaction of tobacco smoking and CYP1A1 Val/Val genotype

Smoking	CYP1A1 (Val/Val)	Case	Control	OR	OR95%CI	χ2	P
No	No	33	47	1.00
No	Yes	24	16	2.14	0.92-4.99	3.73	0.05
Yes	No	44	32	1.96	0.99-3.90	4.29	0.04
Yes	Yes	26	6	6.17	2.14-20.10	14.54	0.00

SIM = 6.17 / (2.14 × 1.96) = 1.47.

Table 6 Interaction of alcohol drinking and CYP1A1Val/Val genotype

Alcohol drinking	CYP1A1 Val/Val	Case	Control	OR	OR95%CI	χ2	P
No	No	50	67	1.00
No	Yes	27	18	2.01	0.94-3.43	3.86	0.05
Yes	No	27	12	3.02	1.31-7.03	8.16	0.00
Yes	Yes	23	4	7.71	2.39-32.16	15.71	0.00

SIM = 7.71 / (2.01 × 3.02) = 1.27.

Table 7 Interaction of CYP1A1 Val/Val genotype and a family history of esophageal cancer

ECFH	CYP1A1 Val/Val	Case	Control	OR	OR95%CI	χ2	P
No	No	65	74	1.00
No	Yes	35	19	2.10	1.04-4.24	5.05	0.03
Yes	No	12	5	2.73	0.84-10.38	3.42	0.06
Yes	Yes	15	3	5.69	1.50-31.72	8.47	0.00

SIA = 5.69 / (2.73 + 2.10 - 1.00) = 1.49.