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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