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Table 4 Meta-analyses of overall population estimates of pancreatic cancer risk associated with ST, using estimates for never smokers if overall population estimates are not availablea

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

Meta-analysis

Estimates Included

Fixed-effect RR (95% CI)

Random-effects RR (95% CI)

Heterogeneity

    

Chisquared (d.f.)

I2

p

All studies

2,3,9,13,19,20,21

1.04(0.86–1.25)

1.03(0.71–1.49)

15.95 (6)

62.4

0.014

All, preferring snuff to chewingb

2,3,9,13,19,20,24

1.04(0.86–1.27)

1.01(0.68–1.50)

16.35 (6)

63.3

0.012

USA or Canada

2,13,19,20,21

0.92(0.65–1.29)

0.89(0.50–1.60)

8.97 (4)

55.4

0.062

Sweden or Norwayc

3,9

1.09(0.87–1.36)

1.20(0.66–2.20)

6.28 (1)

84.1

0.012

Cohort

2,3,9

1.15(0.93–1.42)

1.31(0.82–2.11)

8.03 (2)

75.1

0.018

Case-controld

13,19,20,21

0.70(0.46–1.05)

0.70(0.43–1.13)

3.44 (3)

12.7

0.329

Chewing tobacco

18,21

0.88(0.55–1.40)

1.27(0.33–4.92)

4.76 (1)

79.0

0.029

Snuff

3,9,19,24

1.03(0.83–1.27)

1.02(0.64–1.64)

9.26 (2)

67.6

0.026

ST unspecified

2,13,20

1.14 (0.70–1.84)

0.89(0.33–2.40)

6.94 (2)

71.2

0.031

Overall estimates exclusively

2,3,9,13,19,21

1.03(0.85–1.25)

1.01(0.67–1.54)

15.93 (5)

68.6

0.007

Excluding Third National Cancer Survey Study[16]

2,3,9,19,20,21

1.07(0.89–1.29)

1.13(0.80–1.59)

11.22 (5)

55.4

0.047

  1. a See Table 3 for the individual study estimates
  2. b Where estimates for both snuff and chewing are available
  3. c There was no significant variation by continent (chisquared = 0.70 on 1 d.f., p = 0.404)
  4. d There was significant variation by study type (chisquared = 4.48 on 1 d.f., p = 0.034)