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

Table 21 Kidney cancer; individual effect (relative risk/odds ratio) estimates

	ST use				RR/OR
Source^a	Type^b	Exposure^c	Smoking	Sex	Id.	Cases^d	Estimate (95%CI)	Adjustment factors^e
Cohort studies
Norway cohorts: Boffetta et al. 2005 [26]	Snuff	Current	Any	M	1	9	0.47 (0.23–0.94)	age, smok
		Former			2	13	1.17 (0.63–2.16)
		Ever			3	22	0.72 (0.44–1.18)
Case-control studies
Bennington and Laubscher 1968 [47]	Chew	Use	Any	M	4	5	1.22 (0.39–3.85)^f	none
			Never		5	5	4.80 (1.18–19.59)^f	age
Armstrong et al. 1976 [53]	ST	Current	Any	M	6	6	0.98 (0.30–3.15)^f	none
		Former			7	6	0.73 (0.24–2.20)^f
		Ever			8	12	0.84 (0.37–1.92)^f
Williams and Horm 1977 [55]	ST	Ever	Any	M	9	3	0.59 (0.18–1.90)^f	none
				F	10	1	1.26 (0.17–9.33)^f
McLaughlin et al. 1984 [65]	Chew	Use	Any	M	11	NA	0.40 (0.10–2.60)	age, smok
	Snuff				12	NA	1.70 (0.50–6.00)
	ST				13	NA	1.00 (0.37–2.68)^g
Goodman et al. 1986 [68]	Chew	Ever	Any	M	14^h	13	4.00 (1.13 – 14.17)	age, hosp, race, tadm
Asal et al. 1988 [73]	Snuff	Use	Any	M	15ⁱ	NA	3.60 (1.20–13.30)	age, hosp, race, tadm
					16^j	NA	no association	age, race, tadm
McLaughlin et al. 1995 [99]	ST	Use	Never	M+F	17	11	1.30 (0.60–3.10)	age, bmi, res, sex
Muscat et al. 1995 [100]	Chew	Ever	Any	M	18	14	3.20 (1.10–8.70)	age, edu
Yuan et al. 1998 [106]	ST	Ever	Any	M+F	19	32	1.02 (0.56–1.85)	age, edu, smok

^a Fuller details of the studies are given in Tables 1 and 2.
^b ST implies smokeless tobacco unspecified, or combined snuff use or chewing.
^c Ever, former and current ST use were compared with never ST. Use indicates timing not given and comparison is with non use.
^d 'Id.' is the RR/OR identification number used in Table 22, and 'Cases' is the number of cases in ST users as defined. NA = not available.
^e Abbreviations used: bmi = body mass index, edu = education, hosp = hospital, res = residence, smok = smoking, tadm = time of admission.
^f RR/OR and/or 95% CI estimated from data provided in the source.
^g Estimated assuming ORs for chewing and snuff are independent.
^h The authors also report the results of an analysis adjusting for the effects of the matching factors, body mass index, decaffeinated coffee use and continuous pack-years of cigarette smoking. The authors estimated an OR (95% CI) of 0.87 (0.15–5.14) for the effect of chewing among never smokers of cigarettes, and of 26.00 (4.41–153.00) for the joint effect of pack-years cigarette smoking and chewing tobacco use. These results could not readily be incorporated into the meta-analyses as no overall estimate for chewing tobacco use adjusted for cigarette smoking was available.
ⁱ Analysis uses hospital controls.
^j Analysis uses population controls.
CI = confidence interval; ST = smokeless tobacco; OR = odds ratio; RR = relative risk.

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