Table 1.

Study overview (included studies).

Study	First author, year of publication	Region	Study perioda	Designb	Sex	Case definition (or at risk populationc)d	Controls (or years of follow-upc)	Matching factorse
1	Broders 1920 [74]	USA	up to 1920	CCH	M+F	NS	No lip cancer	NS
2	Moore 1953 [57]	USA	1951–1952	CCH	M	50+ years	No cancer	NS
3	Wynder 1957 [58]	USA	up to 1957	CCH	Mf	NS	Benign diseases, lymphoma, skin and gastrointestinal cancer	Age, rel, ins, ses
4	Peacock 1960 [93]	USA	1952–1958	CCH	M+F	With data on tobacco habits	No oral cancer	Sex, race, ins
5	Vogler 1962 [62]	USA	1956–1957	CCH	M+F	Incident and prevalent	No oral cancer	None
6	Vincent 1963 [94]	USA	up to 1963	CCH	Mg	Incident	Successive gastrointestinal patients	Age
7	Martinez 1969 [95]	Puerto Rico	1966	CCH/P	M+F	Incident in 1966	Patients without cancer and community controls	Age, sex
8	Keller 1970 [75]	USA	1958–1962	CCH	M	Discharged with complete records	No oral cancer	Age, hosp, time
9	Browne 1977 [96]	UK	1957–1971	CCP	M+F	NS	Community controls	Age, sex, occ, area
10	Williams 1977 [97]	USA	1969–1971	CCH	M+F	Incident, Third National Cancer Survey	No tobacco- or alcohol-related cancers	None
11	Wynder 1977 [98]	USA	1969–1975	CCH	M	Histologically confirmed	No tobacco-related diseases	Age, race, area
12	Westbrook 1980 [63]	USA	1955–1975	CCH	F	Incident	Unstated hospital controls	Age, time
13	Winn 1981 [13]	USA	1975–1978	CCH	F	Incident and death certificate	No oral cancer or mental disease	Age, race, type, area
14	Wynder 1983 [99]	USA	1977–1980	CCH	Mf	Histologically confirmed	No tobacco-related diseases	Age, race, hosp, ins
15	Stockwell 1986 [65]	USA	1982	CCP	M+F	Cancer registry 1982	Melanoma or endocrine cancer	None
16	Blot 1988 [100]	USA	1984–1985	CCP	M+F	Incident	Population controls	Age, sex, area, race
17	Spitz 1988 [101]	USA	1985–1987	CCH	M+F	Registered 1985–1986, completed questionnaire, histologically confirmed with squamous cell carcinoma of defined sites	No squamous cell carcinoma	Age, sex
18	Franco 1989 [102]	Brazil	1986–1988	CCH	M+F	Incident, not lip or salivary glands	No cancer or mental disorder	Age, sex, area, time
19	Blomqvist 1991 [103]	Sweden	up to 1991	CCH	M+F	NS	No cancer	Age, sex
20	Maden 1992 [104]	USA	1985–1989	CCP	M	Squamous cell, 18–65 years, with residential telephone	Population controls	Age, time
21	Sterling 1992 [67]	USA	1986	CCP	M+F	Registered in National Mortality Followback Study 1986, age 25+ years	Population controls	None
22	Zahm 1992 [72]	USA	1954–1980	Cohort	M	US veterans who returned questionnaire on tobacco use in 1954 or 1957	Mortality 1954–1980	NA
23	Mashberg 1993 [68]	USA	1972–1983	CCH	M	Incident in 1972–1983, US veterans	No cancer or dysplasia of pharynx, larynx, lung or oesophagus	None
24	Perry 1993h	USA	about 1992	CCH	M+F	NS	Cardiovascular diseases	NS
25	Kabat 1994 [59]	USA	1977–1990	CCH	M+F	Incident	No tobacco-related diseases	Age, sex, race, hosp, time
26	Bundgaard 1995 [105]	Denmark	1986–1990	CCP	M+F	Histologically confirmed	Population controls	Age, sex, area
27	Lewin 1998 [64]	Sweden	1988–1990	CCP	M	Incident and registered, not identified at autopsy	Population controls	Age, area
28	Muscat 1998 [106]	USA	1977–1990	CCH	M+F	Incident, not mentally impaired	No tobacco-related diseases	Age, sex, race, time
29	Schildt 1998 [73]	Sweden	1980–1989	CCP	M+F	Histologically confirmed, not deceased without a relative	Population controls	Age, sex, area, vit
30	Schwartz 1998 [69]	USA	1990–1995	CCP	M+F	Histologically confirmed squamous cell carcinoma, 18–65 years	Population controls	Age, sex
31	Boffetta 2005 [82]	Norway	1966–2001	Cohort	M	Population sample and relatives of migrants to USA	Incidence 1966–2001	NA
32	Henley 2005 [66]	USA	1959–2000	Cohort	M	Never smokers in Cancer Prevention Study I (CPS I) and II (CPS II)	Mortality CPS I : 1959 to 1972 CPS II : 1982 to 2000	NA

^a In studies 3 and 6 the starting year of collection of cases was not given

^b CCH = case control with hospital controls, CCP = case control with population controls

^c For cohort studies

^d NS = not stated

^e NS = not stated, NA = not applicable, rel. = religion, ins. = insurance status, hosp. = hospital, time = period of admission, occ. = occupation, type = incident or decedent, vit. = vital status

^f Exposure data only available for males

^g Insufficient information for females

^h Attributable oral cancer risk due to smokeless tobacco use based on a case-control study at Sinai Hospital in Detroit; unpublished