Table 3.

Overall odd ratio and sub group analysis for case–control studies results

Characteristics	Categories	No. of data sets	Pooled OR (%) (95% CI)	Heterogeneity
				I2%
Overall	–	12	2.077 (0.940–4.587)	75.839
Continent	Africa	1	11.512 (0.600–220.996)	0.000
	Asia	4	6.289 (2.167–18.250)	0.000
	Europe	7	1.125 (0.503–3.113)	82.292
Sample	FFPE	4	2.584 (0.447–14.948)	76.856
	Frozen	6	1.559 (0.511–4.756)	76.355