Systematic review of the relation between smokeless tobacco and cancer in Europe and North America

Table 6 Oesophageal cancer; meta-analysis results

				Heterogeneity
Type of ST (region)^a	Adjustments/restrictions^b	Number of estimates (RR/OR ids)^c	Random-effects RR/OR (95% CI)	χ²	I²	P(χ²)
Any	Overall data	10 (5, 6, 9, 10, 11, 13, 16, 19, 22, 23)	1.25 (1.03–1.51)	10.3	13.0	0.324
	Smoking-adjusted	7 (5, 6, 10, 11, 19, 22, 23)	1.13 (0.95–1.36)	4.4	0.0	0.623
	Never smokers	4 (7, 10, 11, 19)	1.91 (1.15–3.17)	1.0	0.0	0.810
Any (USA)^d	Overall data	6 (9, 10, 11, 13, 16, 19)	1.56 (1.11–2.19)	5.2	4.6	0.387
	Smoking-adjusted	3 (10, 11, 19)	1.89 (0.84–4.25)	1.0	0.0	0.617
	Never smokers	3 (10, 11, 19)	1.89 (0.84–4.25)	1.0	0.0	0.617
Snuff (Scandinavia)	Overall data	4 (5, 6, 22, 23)	1.10 (0.92–1.33)	1.8	0.0	0.61
	Smoking-adjusted	4 (5, 6, 22, 23)	1.10 (0.92–1.33)	1.8	0.0	0.61
	Never smokers	1 (7)	1.92 (1.00–3.68)	--	--	--

^a For each study/sex, the RR/OR for ST from Table 5 was included if available, otherwise that for chewing tobacco or snuff was used.
^b Smoking-adjusted includes estimates for smokers and non-smokers combined, adjusted for smoking if available, and estimates for never smokers otherwise.
^c The actual estimates included are identified by their RR/OR identification numbers as given in Table 5.
^d Includes estimates 10 and 11 from a study in Puerto Rico [49]
CI = confidence interval; ST = smokeless tobacco; OR = odds ratio; RR = relative risk.

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