Table 2.

Gene-environment and Gene-gene Interaction between Smoking and Metabolic Gene SNPs CYP1A1 c.1384A>G and EPHX1 c.337T>C

	No. (%) of Patients	OR (95% CI)	P	OR (95% CI)*	P
Gene-Gene interaction
CYP1A1 c.1384A>G (AA as referent; n=699)
EPHX1 c.337T>C (TT as referent; n=380)
TC + AG/GG	36	1.31 (0.78–2.16)	0.28	1.3 (0.77–2.2)	0.32
CC + AG/GG	18	2.96 (1.57–5.57)	0.001	2.96 (1.49–5.89)	0.002
TC/CC + AG/GG	54	1.61 (1.02–2.55)	0.04	1.6 (0.98–2.6)	0.06
Gene-Smoking interaction
CYP1A1 c.1384A>G (AA as referent; n=699)
Smoking status (never-smoker as referent; n=415)
Ever + AG/GG	35	0.73 (0.46–1.14)	0.17	0.77 (0.47 – 1.27)	0.31
Former + AG/GG	27	0.66 (0.4–1.08)	0.09	0.7 (0.41 – 1.2)	0.2
Current + AG/GG	8	1.11 (0.5–2.49)	0.79	1.15 (0.49 – 2.71)	0.75
Pack-years of smoking (never-smoker as referent; n=415)
≤20 + AG/GG	21	0.9 (0.52–1.54)	0.7	0.83 (0.47 – 1.49)	0.54
>20 + AG/GG	14	0.56 (0.30–1.05)	0.07	0.7 (0.36 – 1.36)	0.29
EPHX1 c.337T>C (TT as referent; n=380)
Smoking status (never-smoker as referent; n=415)
Ever + TC/CC	207	1.37 (1.03–1.81)	0.03	1.35 (1.01 – 1.8)	0.04
Former + TC/CC	176	1.39 (1.04–1.87)	0.03	1.37 (1.01 – 1.85)	0.04
Current + TC/CC	31	1.25 (0.72–2.16)	0.43	1.24 (0.71 – 2.16)	0.44
Pack-years of smoking (never-smoker as referent; n=415)
≤20 + TC/CC	99	1.21 (0.85–1.71)	0.27	1.19 (0.84 – 1.69)	0.32
>20 + TC/CC	107	1.55 (1.09–2.2)	0.01	1.54 (1.07 – 2.21)	0.02

OR, odds ratio; CI, confidence interval.

^*OR adjusted for age, gender and race (White vs. other)