Table 2.

DNA repair gene variation and smoking summary estimates

	Ever-never			Current-Not current			Pack-years			Intensity			Duration
	N	Q p- value	ORz (95% CI)*	N	Q p- value	ORz (95% CI)†	N	Q p-value	ORz (95% CI)‡	N	Q p- value	ORz (95% CI)§	N	Q p-value	ORz (95% CI)□
Gene and SNP
XRCC1
Arg399Gln**	21	0.01	--- †††	11	0.40	1.0 (0.9, 1.1)	9	0.30	1.2 (1.0, 1.5)	4	0.49	1.5 (1.2, 1.9)	2	0.03	--- †††
Arg194Trp††	12	0.62	1.0 (0.9, 1.1)	6	0.68	1.1 (0.9, 1.3)	2	0.73	1.1 (0.7, 1.6)	2	0.89	1.1 (0.8, 1.6)	3	0.47	0.7 (0.5, 0.9)
Arg280His‡‡	5	0.47	1.0 (0.8, 1.2)	4	0.51	0.7 (0.5, 1.1)	3	0.32	1.0 (0.6, 1.5)	1	--	0.9 (0.5, 1.8)	1	--	1.2 (0.6, 2.3)
XPD
Lys751Gln§§	12	0.46	0.9 (0.8, 1.1)	6	0.25	1.1 (0.9, 1.3)	7	0.02	--- †††	0			0
Asp312Asn□□	9	0.79	1.1 (1.0, 1.2)	1	---	1.1 (0.7, 1.9)	4	0.11	1.1 (0.8, 1.5)	0			0
XRCC3
Thr241Met***	9	0.52	1.0 (0.9, 1.2)	7	0.73	0.9 (0.8, 1.1)	4	0.67	0.8 (0.6, 1.2)	0			0

Abbreviations: CI=Confidence interval, na=not applicable, PY=pack-years, OR_z=control-only genotype-smoking odds ratio, Q=Cochran’s test of heterogeneity, N=number of studies, G+=gene is positive for any variant allele G−=negative for variant allele (referent), E+=positive for smoking measures, E−=negative for smoking measure (referent), N=number of studies, SNP=single nucleotide polymorphism, Arg=Arginine, Gln=Glutamine, Trp=Tryptophan, His=Histidine, Met=methionine, Asp=Aspartic acid, Asn=Asparagine

^*Fixed effects summary estimates for G+/G− vs. E+/E−. G− is homozygous for the common allele (ref), G+ is the genotype with 1 or 2 variant alleles, E− (ref) is never smoker and E+ is ever smoking

^†Fixed effects summary estimates for G+/G− vs. E+/E−. G− is homozygous for the common allele (ref), G+ is the genotype with 1 or 2 variant alleles, E− (ref) is not current smoker and E+ is current smoking

^‡Fixed effects summary estimates for G+/G− vs. E+/E−. G− is homozygous for the common allele (ref), G+ is the genotype with 1 or 2 variant alleles, E− (ref) is lowest non-zero PY category and E+ is highest category of PY

^§Fixed effects summary estimates for G+/G− vs. E+/E−. G− is homozygous for the common allele (ref), G+ is the genotype with 1 or 2 variant alleles, E− (ref) is lowest non-zero category of intensity (cig/day) and E+ is highest category of smoking intensity.

^□Fixed effects summary estimates for G+/G− vs. E+/E−. G− is homozygous for the common allele (ref), G+ is the genotype with 1 or 2 variant alleles, E− (ref) is lowest non-zero category of duration(yrs) and E+ is highest category of smoking duration.

^**Arg/Arg v. any Gln

^††Arg/Arg v. any Trp

^‡‡Arg/Arg v. any His

^§§Lys/lys v. any Gln

^□□Asp/Asp v. any Asn

^***Thr/Thr v. any Met

^†††Studies too heterogeneous for fixed effects summary estimate