Table 2. Stratified analyses of the -607C/A polymorphisms in IL-18 gene promoter with cancer risk.

	A vs. C			AA vs. CC			CA vs. CC			AA vs. CC/CA			AA/CA vs. CC
	Study	OR(95% CI)	Phet	Study	OR(95% CI)	Phet	Study	OR(95% CI)	Phet	Study	OR(95% CI)	Phet	Study	OR(95% CI)	Phet
Overall	23	1.088 (0.987-1.200)	0.003	23	1.139 (0.948-1.369)	0.023	23	1.221 (1.096-1.360)*	0.219	23	0.995 (0.851-1.163)	0.025	23	1.203 (1.057-1.369)*	0.064
Ethnicity
Asian	17	1.107 (0.972-1.260)	0.001	17	1.196 (0.936-1.530)	0.007	17	1.191 (1.047-1.356)*	0.487	17	1.035 (0.854-1.255)	0.011	17	1.197(1.023,1.401)*	0.088
Caucasian	5	1.041 (0.909-1.193)	0.336	5	1.023 (0.779-1.343)	0.473	5	1.294 (0.906-1.848)	0.041	5	0.890 (0.696-1.138)	0.620	5	1.198 (0.888-1.618)	0.083
African	1	1.076 (0.790-1.464)	NA	1	1.065 (0.558-2.030)	NA	1	1.578 (0.951-2.620)	NA	1	0.793 (0.455-1.382)	NA	1	1.421 (0.877-2.301)	NA
Source of controls
Hospital based	9	1.247 (1.022-1.523)*	0.005	9	1.329 (0.924-1.912)	0.009	9	1.353 (1.115-1.642)*	0.435	9	1.135 (0.871-1.479)	0.044	9	1.362(1.134,1.635)*	0.116
Population based	14	1.021 (0.941-1.107)	0.124	14	1.012 (0.832-1.231)	0.196	14	1.165 (1.024-1.327)*	0.189	14	0.911 (0.764-1.087)	0.154	14	1.114(0.986,1.258)	0.190
Sample size
Small	18	1.092 (0.955-1.249)	<0.001	18	1.149 (0.896-1.472)	0.008	18	1.223 (1.036-1.445)*	0.085	18	1.006 (0.813-1.246)	0.008	18	1.200 (1.006-1.430)*	0.016
Large	5	1.032 (0.918-1.161)	0.269	5	1.051 (0.836-1.320)	0.313	5	1.134 (0.863-1.490)	0.042	5	0.980 (0.824-1.164)	0.810	5	1.107 (0.862-1.421)	0.052
Cancer types
Prostate cancer	2	0.993 (0.852-1.157)	0.385	2	0.993 (0.732-1.346)	0.331	2	1.039 (0.639-1.690)	0.081	2	0.985 (0.773-1.254)	0.896	2	1.027 (0.675-1.565)	0.109
Esophageal cancer	2	1.095 (0.926-1.293)	0.852	2	1.111 (0.799-1.544)	0.783	2	1.371 (1.045-1.800)*	0.528	2	0.945 (0.713-1.253)	0.591	2	1.289 (1.002-1.658)*	0.700
Nasopharyngeal carcinoma	4	1.144 (0.985-1.328)	0.845	4	1.305 (0.961-1.772)	0.759	4	1.330 (1.029-1.719)*	0.704	4	1.082 (0.842-1.391)	0.547	4	1.323 (1.037-1.687)*	0.823
Colorectal cancer	3	1.066 (0.883-1.286)	0.262	3	1.092 (0.664-1.795)	0.213	3	1.460 (0.898-2.371)	0.097	3	0.896 (0.638-1.259)	0.359	3	1.337 (0.865-2.068)	0.118
Breast cancer	2	1.147 (0.904-1.456)	0.726	2	1.332 (0.800-2.216)	0.438	2	1.169 (0.814-1.678)	0.532	2	1.225 (0.716-2.096)	0.274	2	1.204 (0.854-1.696)	0.784
Cervical cancer	2	1.396 (0.208-9.382)	<0.001	2	1.890 (0.069-51.901)	<0.001	2	1.397 (0.644-3.031)	0.241	2	1.403 (0.090-21.882)	<0.001	2	1.653 (0.241-11.339)	0.003
Other cancers	8	1.044 (0.910-1.196)	0.200	8	0.978 (0.717-1.334)	0.223	8	1.100 (0.803-1.507)	0.014	8	0.935 (0.738-1.183)	0.804	8	1.075 (0.795-1.454)	0.012

OR: odds ratio; CI: confidence intervals; Phet: P value for heterogeneity; * OR with statistical significance