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