Interaction models of CYP1A1, GSTM1 polymorphisms and tobacco smoking in intestinal gastric cancer

Table 1 Characteristics of the interviewed subjects

	Characteristics	Gastric cancer cases (114)	Control subjects (693)	OR (95%CI)
Median age	yr±SD	59±10	53±10	1.1 (1.0–1.1)1
	Min (yr)	35	30
	Max (yr)	82	78
Gender	Female (%)	38 (33)	383 (55)	1.0 (Ref.)
	Male (%)	76 (67)	310 (45)	1.2 (0.7–2.1)
	F/M ratio	1:2	01:00.8
Educational level	>5 yr	44 (38.6)	246 (35.5)	1.0 (Ref.)
	≤5 yr	70 (61.4)	447 (64.5)	1.0 (0.6–1.7)
Occupation
	Manual	51 (44.7)	375 (54.1)	1.0 (Ref.)
	Office	9 (7.9)	87 (12.6)	0.6 (0.2–1.3)
	Retired	54 (47.4)	231 (33.3)	1.2 (0.7–1.9)
Marriage status
	Married	100 (87.7)	649 (94.7)	1.0 (Ref.)
	Divorce or bereft spouse	14 (12.3)	36 (5.3)	1.4 (0.6–3.0)
Family history of cancer
	No	84 (76.4)	613 (90.3)	1.0 (Ref.)
	Yes	26 (23.6)	66 (9.7)	3.9 (2.1–7.3)1
BMI (kg/m2)
	<20	56 (49.1)	95 (13.7)	1.0 (Ref.)
	20–	44 (38.6)	254 (36.7)	0.3 (0.2–0.5)1
	23–	14 (12.3)	344 (49.6)	0.1 (0.03–0.12)1
Tobacco smoking habits
	Never	51 (44.7)	437 (63.0)	1.0 (Ref.)
	Current	36 (31.6)	225 (32.5)	0.6 (0.3–1.3)
	Former	27 (23.7)	31 (4.5)	2.4 (1.0–5.8)1
Amount of former smoking (pack years)
	No	87 (76.4)	662 (95.6)	1.0 (Ref.)
	1–19	7 (6.1)	10 (1.4)	2.6 (0.8–8.6)
	20–29	8 (7.0)	11 (1.6)	3.1 (1.1–9.0)1
	≥30	12 (10.5)	10 (1.4)	4.4 (1.7–11.9)1
Alcohol drinking habits
	Never	78 (68.5)	505 (72.9)	1.0 (Ref.)
	Current	11 (9.6)	156 (22.5)	0.2 (0.1–0.5)1
	Former	25 (21.9)	32 (4.6)	2.3 (1.2–4.7)1
Plasma H pylori CagA antibody
	Negative	136 (82.4)	107 (49.3)	1.0 (Ref.)
	Positive	29 (17.6)	110 (50.7)	0.2 (0.1–0.3)1
CYP1A1 genotype
	Ile/Ile	70 (62.5)	412 (61.0)	1.0 (Ref.)
	Ile/Val	36 (32.1)	226 (33.4)	0.9 (0.5–1.4)
	Val/Val	6 (5.4)	38 (5.6)	0.7 (0.2–1.8)
GSTM1 genotype
	Present	41 (36.6)	314 (46.5)	1.0 (Ref.)
	Null	71 (63.4)	361 (53.5)	2.0 (1.2–3.1)1

¹Showed significant difference after adjusting co-variables.

Table 2 Interaction models of CYP1A1 and GSTM1 polymorphism with former smoker in intestinal gastric cancer

Genotype	Former smoker	Cases	Controls	OReg	95%CI
Ile1	No	57	391	1	Ref.
Val2	No	29	254	0.7	0.4–1.1
Ile	Yes	13	21	1.8	0.7–4.3
Val	Yes	13	10	5.05	1.9–13.4
Present3	No	31	302	1	Ref.
Null4	No	54	345	1.9	1.1–3.1
Present	Yes	10	12	3.5	1.2–10.1
Null	Yes	17	16	8.46	3.4–20.9

¹[Ile]: CYP1A1 homozygous (Ile/Ile) genotype;

²[Val]: CYP1A1 heterozygous (Ile/Val)+homozygous (Val/Val) genotypes;³[present]: present genotype for GSTM1;

⁴[null]: null genotype for GSTM1;

⁵adjusted by age, gender, living areas, family history of cancer, and former alcohol drinking; χ²_trend=24.0, df=1, P=0.00; γ=1.61/0.57=2.8;

⁶adjusted by age, gender, living areas, family history of cancer, and former alcohol drinking; χ²_trend=45.7, df=1, P=0.00; γ=2.13/0.63=3.4.

Table 3 FPRP values for interactions between GSTM1 and former tobacco smoking in intestinal gastric cancer

GSTM1	Former	Observed	Assuming	Prior probability
genotype	Smoking	OR	OR	0.25	0.1	0.01	0.001	0.0001	0.00001
GSTM1 null	No	1.9	1.2	0.4811	0.7362	0.968	0.997	1.000	1.000
			1.5	0.151	0.348	0.854	0.983	0.998	1.000
			2.0	0.05	0.136	0.634	0.946	0.994	0.999
GSTM1 present	Yes	3.5	2.4	0.202	0.432	0.893	0.988	0.999	1.000
			3.0	0.137	0.322	0.84	0.981	0.998	1.000
			4.0	0.093	0.236	0.773	0.972	0.997	1.000
GSTM1 null	Yes	8.4	4.8	0.000	0.000	0.004	0.04	0.293	0.805
			6.0	0.000	0.000	0.002	0.02	0.168	0.669
			8.4	0.000	0.000	0.001	0.009	0.087	0.487

¹Bold with ¹Bold with gray fill color indicate “noteworthy at the 0.5 FPRP level”;

²with no fill color indicate “not noteworthy at the 0.5 FPRP level”.