From: Systematic review of the relation between smokeless tobacco and cancer in Europe and North America
 | ST use |  |  | RR/OR | ||||
---|---|---|---|---|---|---|---|---|
Sourcea | Typeb | Exposurec | Smoking | Sex | Id. | Casesd | Estimate (95%CI) | Adjustment factorse |
Cohort studies | Â | Â | Â | Â | Â | Â | Â | Â |
Norway cohorts: Boffetta et al. 2005 [26] | Snuff | Current | Any | M | 1 | 40 | 0.72 (0.52–1.06) | age, smok |
 |  | Former |  |  | 2 | 30 | 0.98 (0.66–1.47) |  |
 |  | Ever |  |  | 3 | 69 | 0.83 (0.62–1.11) |  |
Case-control studies | Â | Â | Â | Â | Â | Â | Â | Â |
Lockwood 1961 [43] | ST | Current | Never | M | 4 | 2 | 0.35 (0.07–1.77)f | none |
Wynder et al. 1963 [46] | Chew | Ever | Any | M | 5 | 33 | 1.42 (0.82–2.47)f | none |
 | Snuff |  |  |  | 6 | 6 | 0.66 (0.23–1.88)f |  |
 | ST |  |  |  | 7 | 39 | 1.21 (0.74–1.98)g |  |
Dunham et al. 1968 [48] | ST | Ever | Never | M | 8 | 4 | 2.57 (0.52–12.54)f | race |
 |  |  |  | F | 9 | 3 | 0.58 (0.14–2.45)f |  |
Cole et al. 1971 [51] | Chew | Ever | Any | M | 10 | 46 | no associationh | age |
 | Snuff |  |  |  | 11 | 3 | no associationi |  |
Williams and Horm 1977 [55] | ST | Ever | Any | M | 12 | 29 | 1.67 (1.09–2.55)f | age, race, smok |
 |  |  |  | F | 13 | 1 | 0.82 (0.11–6.02)f | none |
Wynder and Stellman 1977 [56] | Chew | Ever | Any | M | 14 | 47 | 0.87 (0.63–1.21)f | none |
 | Snuff |  |  |  | 15 | 11 | 0.69 (0.36–1.31)f |  |
 | ST |  |  |  | 16 | 58 | 0.82 (0.61–1.10)g |  |
Howe et al. 1980 [58] | Chew | Ever | Any | M | 17 | NA | 0.90 (0.50–1.60) | age, smok |
Mommsen and Aagaard 1983 [62] | Chew | Ever | Any | M | 18 | 39 | 1.70 (1.00–2.90) | age, res |
Hartge et al. 1985 [66] | Chew | Ever | Neverj | M | 19 | 40 | 1.02 (0.67–1.54) | age, race, res, smokj |
 | Snuff |  |  |  | 20 | 11 | 0.77 (0.38–1.56) |  |
 | ST |  |  |  | 21 | 51 | 1.14 (0.80–1.61)g | none |
Kabat et al. 1986 [69] | Snuff | Ever | Never | F | 22 | 3 | 10.40 (1.07–101.46) | none |
Slattery et al. 1988 [77] | Chew | Ever | Any | M | 23 | 20 | 0.76 (0.42–1.39) | smokk |
 |  |  | Never |  | 24 | 1 | 0.36 (0.05–2.82)l | none |
 | Snuff | Ever | Any |  | 25 | 16 | 0.92 (0.47–1.82) | smokk |
 |  |  | Never |  | 26 | 2 | 2.74 (0.45–16.69)m | none |
 | ST | Ever | Any |  | 27 | 36 | 0.82 (0.52–1.29)g | smokk |
 |  |  | Never |  | 28 | 3 | 0.86 (0.24–3.07)g | none |
Burch et al. 1989 [79] | Chew | Ever | Any | M | 29 | 26 | 0.60 (0.34–1.06) | age, res, smok |
 | Snuff |  |  |  | 30 | 9 | 0.47 (0.21–1.07) |  |
 | ST |  |  |  | 31 | 35 | 0.54 (0.34–0.87)g |  |