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

Table 16 Lung 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	9 (2, 3, 6, 11, 13, 19, 20, 21, 24)	0.96 (0.73–1.27)	53.2	85.0	< 0.001
	Smoking-adjusted	6 (2, 3, 6, 11, 13, 20)	0.99 (0.71–1.37)^d	28.7	82.6	< 0.001
	Never smokers	5 (2, 3, 6, 12, 16)	1.34 (0.80–2.23)	11.5	65.3	0.021
Any (USA)	Overall data	6 (2, 3, 6, 20, 21, 24)	1.22 (0.82–1.83)	18.5	73.0	0.002
	Smoking-adjusted	4 (2, 3, 6, 20)	1.38 (0.72–2.64)	16.5	81.9	0.001
	Never smokers	3 (2, 3, 6)	1.79 (0.91–3.51)	6.2	67.8	0.045
Snuff (Scandinavia)	Overall data	2 (11, 13)	0.71 (0.66–0.76)	0.9	0.0	0.354
	Smoking-adjusted	2 (11, 13)	0.71 (0.66–0.76)	0.9	0.0	0.354
	Never smokers	2 (12, 16)	0.82 (0.52–1.28)	0.1	0.0	0.798

^a For each study/sex, the RR/OR for ST from Table 15 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 15.
^d Test for publication bias 0.05 ≤ P < 0.1.
CI = confidence interval; ST = smokeless tobacco; OR = odds ratio; RR = relative risk.

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