Table 2.

Combined relative risks and 95%CI for esophageal cancer associated with red meat or processed meat by other factors in both cohort and case-control studies

	Red meat				Processed meat
Factors	Studies (n)	Ref.	RR (95%CI)	P for heterogeneity	Studies (n)	Ref.	RR (95%CI)	P for heterogeneity
Histological subtypes
EAC	9	[11-13,15,20,22,24,25,32]	1.42 (1.02-1.98)	0.19	8	[11-13,15,20,24,25,32]	1.38 (1.07-1.78)	0.3
ESCC	9	[11,12,16,17,19,21,23,27,29]	1.55 (1.10-2.17)		7	[11,12,16,19,21,27,33]	1.08 (0.80-1.44)
Study location
Asia	6	[14,17,18,19,23,26]	1.33 (1.09-1.62)	0.67	5	[19,33,34,36,37]	1.09 (0.61-1.95)	0.65
Europe	6	[11,13,20,21,27,30]	1.33 (0.86-2.07)		7	[11,13,20,21,27,30,35]	1.49 (0.99-2.23)
United States	7	[12,15,22,24,25,31,32]	1.32 (1.03-1.70)		5	[12,15,21,25,32]	1.30 (1.08-1.57)
South America	3	[16,28,29]	2.20 (0.48-10.04)		1	[16]	0.76 (0.51-1.13)
Sex
Male	3	[11,23,26]	1.26 (0.66-2.41)	0.88	2	[11,33]	1.24 (0.58-2.65)	0.14
Female	2	[11,23]	1.31 (0.78-2.21)		1	[11]	0.61 (0.33-1.13)
Both	19	[12-22,24,25,27-32]	1.42 (1.17-1.71)		16	[12,13,15,16,19-21,24,25,27,30,32,34-37]	1.43 (1.15-1.77)
Study quality1
≥ 7	8	[11-14,16,18,20,22]	1.60 (1.20-2.13)	0.23	6	[11-13,16,20,25]	1.20 (0.88-1.62)	0.42
< 7	14	[15,17,19,21,23-32]	1.25 (1.02-1.54)		12	[15,19,21,24,27,30,32-37]	1.43 (1.11-1.86)

¹Study quality was assessed using the Newcastle-Ottawa Scale (range, 1-9 stars); RR: Relative risk; ESCC: Esophageal squamous cell carcinoma; EAC: Esophageal adenocarcinoma.