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

Table 3 RR/OR of pancreatic cancer associated with smokeless tobacco use

Study^a	ST use		Smoking	Sex	RR/OR
	Type^b	Exposure^c			No.	Cases^d	Estimate (95% CI)	Notes
Cohort studies					RR
US Veterans [19]	ST	Use	Never	M	1	NA	1.65	e, f
Lutheran Brotherhood [9]	ST	Ever	Any	M	2	16	1.70(0.90–3.10)
Norway Cohorts [10]	Snuff	Ever	Any	M	3	45	1.67(1.12–2.50)	g
		Former	Any		4	18	1.80(1.04–3.09)
		Current	Any		5	27	1.60(1.00–2.55)
		Ever	Never		6	3	0.85(0.24–3.07)
		Ever	Former		7	14	1.37(0.59–3.17)
		Ever	Current		8	28	1.86(1.13–3.05)
Swedish Construction Workers [11]	Snuff	Ever	Any	M	9	NA	0.90(0.70–1.20)
		Ever	Never		10	20	2.00(1.20–3.30)
		Former	Never		11	2	1.40(0.40–5.90)
		Current	Never		12	18	2.10(1.20–3.60)
Case-control studies					OR
Third National Cancer Survey [16]	ST	Ever	Any	M	13	3	0.29(0.09–0.92)	h
Louisiana [20]	Chewing	Use	Any	M+F	14	NA	"No excess risk"
	Snuff	Use	Any		15	NA	"No excess risk"
Washington State [12]	Chewing	Ever	Any	M	16	NA	0.80 (Not sig.)	i
Quebec [21]	Chewing	Use	Any	M+F	17	NA	"Not associated with increased risk"
Nine Hospital [13]	Chewing	Ever	Never^j	M	18	6	2.82(0.95–9.39)	k
	Snuff	Ever	Any		19	2	1.32(0.22–7.93)	h
Fifteen County [14]	ST	Ever	Never	M+F	20	5	1.10(0.40–3.10)	l
Texas [15]	Chewing	Ever	Any	M+F	21	34	0.70(0.40–1.10)
		Ever	Ever		22	24	0.70(0.40–1.20)
		Ever	Never		23	10	0.60(0.30–1.40)
	Snuff	Ever	Any		24	18	0.60(0.30–1.10)
		Ever	Ever		25	14	0.70(0.30–1.40)
		Ever	Never		26	4	0.50(0.10–1.50)

^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 are compared with never ST. Use indicates timing not given and comparison is with non use
^d Cases in ST users as defined, NA = not available
^e The abstract suggests the results are for never smokers, but this is not totally clear. The population included < 0.5% females. In earlier reports from this study [30] RRs were reported of 3.3 (statistically significant) for former ST users, and of 2.1 (not significant) for current ST users, based on, respectively, 7 and 5 cases in the exposed group
^f Confidence intervals could not be calculated
^g In earlier reports the risk of histologically-reported pancreatic cancer in regular ST users was stated to be 2.2 ("significant") [30] and 2.9 (trend p = 0.06) [31]
^h Estimated from data provided
ⁱ Additional adjustment for age and dietary factors did not materially affect the odds ratios
^j Includes long term (> 10) years quitters
^k Personal communication from the author
^l The authors also reported an adjusted OR of 1.4 (0.5–3.6) for the comparison (among never cigarette smokers) of ever used ST, but may have used pipe or cigar versus never used ST, pipe or cigar

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