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Table 3 Study details and effect estimates.

From: Meta-analysis of the relation between European and American smokeless tobacco and oral cancer

Study First author, year of publication Method of exposure assessment Cancer site Adjustment factorsa Exposure (period) Sex Cases/Controlsb OR/RRc(95% CI)
1 Broders
1920 [74]
NS Lip Smoking Chewing (NS) M+F 537/500 2.05 (1.48–2.83)de
     None Snuff (NS) M+F 537/500 1.76 (0.12–26.2)ef
     None Smokeless (NS) M+F 537/500 2.05 (1.48–2.83)efg
2 Moore
1953 [57]
Interview Buccal mucosa, gum, floor of mouth None Smokeless (20+ years) M 112/38 3.00 (1.37–6.54)f
3 Wynder
1957 [58]
Interview Lip, floor of mouth, gum, buccal mucosa, tongue, palate, tonsil, pharynx Smokingh Chewing (ever) M 525/186 2.00 (1.16–3.47)ef
4 Peacock
1960 [93]
Interview Buccal mucosa, alveolar ridge, floor of mouth Age, ins. Smokeless (20+ years) M 25/191 3.06 (1.08–8.63)di
       F 20/172 2.00 (0.66–6.01)di
5 Vogler
1962 [62]
Interview or questionnaire Lip, buccal mucosa, tongue, palate, gingiva, floor of mouth, minor salivary glandsk None Chewing (ever) M 14/402 7.38 (4.31–12.62)dij
      Snuff (ever) F 75/826 38.28 (21.49–68.15)dei
6 Vincent
1963 [94]
Interview Oral cavity, pharynx None Snuff (NS) M 66/100 4.22 (1.41–12.63)fi
7 Martinez
1969 [95]
Interview Mouth and pharynx Smokingl Chewing (last 20 years) M 18/81 2.29 (0.62–8.48)fim
       F 16/79 0.34 (0.04–2.79)fim
8 Keller
1970 [75]
Hospital records Lip Smoking Smokeless (NS) M 258/207 3.63 (1.02–12.95)d
9 Browne
1977 [96]
Interview, proxy interview Buccal mucosa, upper alveolus and hard palate, lower alveolus, floor of mouth, pillar of fauces, soft palate, unspecified or multiple None Chewing (NS) M+F 75/150 0.67 (0.27–1.66)f
10 Williams
1977 [97]
Interview Lip, tongue, salivary glands, gum, mouth, pharynx None Smokeless (ever) M 190/1788 0.91 (0.53–1.56)fgi
       F 79/3188 1.54 (0.37–6.42)fgi
11 Wynder
1977 [98]
Interview Oral cavity None Chewing (ever) M 591/2560 1.15 (0.85–1.55)f
      Snuff (ever) M 591/2560 0.62 (0.32–1.22)f
      Smokeless (ever) M 591/2560 1.02 (0.78–1.34)fgn
12 Westbrook
1980 [63]
Hospital records Buccal mucosa, gum None Snuff (ever) F 55/55 540.0 (60.97–4782.82)f
13 Winn
1981 [13]
Interview, proxy interview Mouth and pharynx Smoking, race Snuff (ever) F 232/410 2.67 (1.83–3.90)d
14 Wynder
1983 [99]
Interview Oral and pharyngeal None Chewing (ever) M 414/414 1.00 (0.62–1.61)ef
      Snuff (ever) M 414/414 0.42 (0.11–1.65)f
      Smokeless (ever) M 414/414 0.90 (0.57–1.41)efgn
15 Stockwell
1986 [65]
Medical records Lip, tongue, salivary glands, gum, floor of mouth, other parts of mouth, pharynx None Smokeless (ever) M+F 1462/8285 2.02 (1.01–4.02)fi
16 Blot
1988 [100]
Interview, proxy interview Oral and pharyngeal None Smokeless (ever) M 762/837 0.85 (0.57–1.26)ef
       F 352/431 3.44 (1.09–10.91)ef
17 Spitz
1988 [101]
Questionnaire Larynx, tongue, orohypopharynx, oral cavityo None Chewing (ever) M+F 185/185 1.00 (0.54–1.85)f
     NS Snuff (ever) M+F 185/185 3.40 (1.00–10.90)p
     None Smokeless (ever) M+F 185/185 1.05 (0.57–1.91)fg
18 Franco
1989 [102]
Interview Oral cavity, tongue, gum, floor of mouth None Smokeless (ever) M+F 232/464 1.40 (0.59–3.33)f
19 Blomqvist
1991 [103]
Questionnaire Lower lip Smokingl Snuff (ever) M+F 14/10 0.67 (0.08–5.75)f
20 Maden
1992 [104]
Interview Lip, tongue, gum, floor of mouth, oropharynx, other parts of mouth Age Smokeless (ever) M 131/136 4.50 (1.50–14.30)p
21 Sterling
1992 [67]
Interview (controls), proxy interview (cases) Oral and pharyngeal Smoking, sex, race, age, alc, occ. Smokeless (100+ times) M+F 6976/NS 1.04 (0.41–2.68)q
     Sex, race, age Snuff (ever) M+F 6976/NS 2.42 (1.28–4.59)p
22 Zahm
1992 [72]
Questionnaire Buccal cavity, pharynx Age, time Smokeless (ever) M 129/248046 4.11 (2.90–5.84)r
23 Mashberg
1993 [68]
Interview Oral cavity, oropharynx Smoking, age, race, alc. Snuff (ever) M 359/2280 0.80 (0.40–1.90)p
      Chewing (ever) M 359/2280 1.00 (0.70–1.40)p
      Smokeless (ever) M 359/2280 0.96 (0.70–1.33)nq
24 Perry
1993s
NS Oral Smoking, age, sex, race, alc, occ. Smokeless (100+ times) M+F 133/678 1.43 (0.64–3.21)q
25 Kabat
1994 [59]
Interview Tongue, floor of mouth, gums, gingiva, buccal mucosa, palate, retromolar area, tonsil and other pharynx Smokingl Snuff (ever) M+F 195/918 4.79 (1.19–19.30)f
     Smoking Chewing (ever) M 1097/2075 1.11 (0.81–1.53)de
26 Bundgaard
1995 [105]
Questionnaire Retromolar area, buccal mucosa, floor of mouth, hard palate, upper alveolus, lower alveolus, tongue None Chewing (ever) M+F 161/400 1.44 (0.59–3.51)d
27 Lewin
1998 [64]
Interview Oral and pharyngeal Smoking, age, area, alc. Snuff (ever) M 266/641 0.98 (0.63–1.50)r
28 Muscat
1998 [106]
Interview Major salivary gland None Chewing (ever) M+F 128/114 0.89 (0.18–4.49)d
      Smokeless (ever) M+F 128/114 1.19 (0.26–5.45)dgn
29 Schildt
1998 [73]
Questionnaire from next-of-kin for deceased cases/controls Lip, tongue, gum, mouth Smoking, alc. Snuff (ever) M+F 354/354 0.80 (0.50–1.30)p
     None Chewing (ever) M+F 354/354 0.60 (0.20–2.00)p
      Smokeless (ever) M+F 354/354 0.87 (0.61–1.25)fgn
30 Schwartz
1998 [69]
Interview Tongue, gum, floor of mouth, tonsils, oropharynx, other parts of mouth Smoking, age, alc, sex Smokeless (ever) M 165/302 1.00 (0.40–2.30)p
31 Boffetta
2005 [82]
Questionnaire Oral and pharyngeal Smoking, age Snuff (ever) M 34/10136 1.10 (0.50–2.41)p
32 Henley
2005 [66]
Questionnaire Oral and pharyngeal Smokingl, age, race, educ., alc, exer, asp, bmi, diet, occt. Smokeless (current) M (CPS-I) 13/77407 2.02 (0.53–7.74)p
      Smokeless (ever) M (CPS-II) 46/114809 0.90 (0.12–6.71)p
  1. a alc = alcohol consumption, asp = aspirin, bmi = body mass index, educ = education, exer = exercise, ins = insurance status, occ = occupation
  2. b At risk population for cohort studies
  3. c OR = odds ratio (case-control studies), RR = relative risk (cohort studies)
  4. d Estimated from multiple independent 2 × 2 tables using fixed-effect meta-analysis
  5. e Numbers of exposed and unexposed cases and controls estimated from proportions exposed given numerically
  6. f Estimated from 2 × 2 table
  7. g Numbers of exposed cases and controls combined over levels of exposure
  8. h Analysis based on smokers only (only one SLT user was a non-smoker)
  9. i Numbers of cases combined over cancer types specified
  10. j Numbers of exposed and unexposed cases and controls estimated from proportions exposed given graphically
  11. k Due to the joint reporting of pharynx and larynx cases, both sites excluded from analysis
  12. l Analysis based on non-smokers only
  13. m Note that in Table 13 of source chewing only data for mouth cancer wrongly given under pipe only
  14. n Calculated assuming no-one chewed tobacco and used snuff
  15. o Larynx cases cannot be sorted out due to incomplete reporting
  16. p As reported by the authors
  17. q Estimated from non-independent relative risks by level of exposure using method of Fry and Lee
  18. r Estimated from non-independent relative risks for cancer types using method of Fry and Lee
  19. s Attributable oral cancer risk due to smokeless tobacco use based on a case-control study at Sinai Hospital in Detroit; unpublished
  20. t Occupation only adjusted for in CPS-II