Table 4. Stratified analyses of relative risk of different cancer.

	No of reports	Relative risk (95% CI)	P for heterogeneity	I2	P for test
Breast cancer	11	1.15 (1.05–1.25)	0.345	17.3%	< 0.001
Subgroup analyses for Breast cancer
Study location
Caucasia	7	1.17 (1.08–1.26)	0.258	25.6%	< 0.001
Asia	4	1.09 (1.03–1.16)	0.631	0.0%	< 0.001
Study design
Case–control	8	1.05 (1.01–1.09)	0.214	23.6%	< 0.001
Cohort	3	1.19 (1.12–1.28)	0.447	0.0%	< 0.001
Study quality
Score ≥ 7	7	1.06 (1.02–1.10)	0.215	24.3%	< 0.001
Score < 7	4	1.19 (1.11–1.28)	0.474	0.0%	< 0.001
No of participants
≥ 10 000	8	1.05 (1.01–1.09)	0.214	23.6%	< 0.001
< 10 000	3	1.19 (1.12–1.28)	0.447	0.0%	< 0.001
No of cases
≥ 1500	9	1.07 (1.02–1.12)	0.101	33.6%	< 0.001
< 1500	2	1.18 (1.10–1.26)	0.673	0.0%	< 0.001
Ovarian cancer	8	1.17 (1.09–1.25)	0.000	74.5%	< 0.001
Subgroup analyses for Ovarian cancer
Study location
Caucasia	4	1.22 (1.15–1.30)	0.008	80.2%	< 0.001
Asia	4	1.11 (1.05–1.17)	0.657	0.0%	< 0.001
Study design
Case–control	5	1.14 (1.02–1.28)	0.000	84.4%	0.012
Cohort	3	1.19 (1.12–1.28)	0.447	0.0%	< 0.001
Study quality
Score ≥ 7	3	1.19 (1.12–1.28)	0.447	0.0%	< 0.001
Score < 7	5	1.14 (1.02–1.28)	0.000	84.4%	0.012
No of participants
≥ 10 000	3	1.19 (1.12–1.28)	0.447	0.0%	< 0.001
< 10 000	5	1.14 (1.02–1.28)	0.000	84.4%	0.012
No of cases
≥ 1500	3	1.19 (1.12–1.28)	0.447	0.0%	< 0.001
< 1500	5	1.14 (1.02–1.28)	0.000	84.4%	0.012
Colon cancer	4	1.07 (1.02–1.13)	0.361	10.4%	< 0.001
Renal cancer	4	1.31 (1.15–1.49)	0.198	25.7%	< 0.001
Malignant melanoma	3	1.10 (1.03–1.17)	0.715	0.0%	< 0.001
Brain cancer	4	2.06 (1.76–2.43)	0.000	86.1%	< 0.001
Esophagus cancer	4	1.55 (1.30–1.85)	0.679	0.0%	< 0.001
Prostate cancer	3	1.26 (1.16–1.37)	0.000	79.5%	< 0.001
Liver cancer	3	1.22 (1.13–1.31)	0.000	62.9%	< 0.001
Stomach cancer	2	1.17 (1.03–1.32)	0.174	45.6%	< 0.001
Pancreatic cancer	2	1.39 (1.17–1.64)	0.813	0.0%	< 0.001
Lung cancer	3	1.20 (1.12–1.28)	0.000	89.8%	< 0.001