A quantitative evaluation of the aetiological role of betel quid in oral carcinogenesis.
Computer aided search and review of bibliographies of published papers and monographs revealed 17 case control studies of oral cancer and betel quid chewing from 1933 to 1990. Studies were assessed and site specific risk of oral cancer associated with chewing betel quid with and without tobacco in the quid among smokers and non-smokers was computed. Tobacco smoking and chewing betel quid containing tobacco arose as important risk factors for oral cancer, betel quid without tobacco significantly increased risk in only one study. Heterogeneity in estimates of risk among studies was reduced by restricting analysis to those with more exact definition of exposure and site of the cancer. Variation in risk among studies reflects bias in selection and inadequate definition of exposure and tumour site and an inability to control effectively for confounding. Further studies, addressing these issues are advised, to clarify the role of betel quid without tobacco as a carcinogen, alone and in combination with tobacco smoke.
Thomas
S
S
Epidemiology Unit, Queensland Institute of Medical Research, 300 Herston Road, Brisbane, Queensland 4029, Australia.
Wilson
A
A
D001114:Areca / Q000009:adverse effects*; D016022:Case-Control Studies; D002471:Cell Transformation, Neoplastic; D015986:Confounding Factors, Epidemiologic; D016021:Epidemiologic Studies; D006801:Humans; D009062:Mouth Neoplasms / Q000209:etiology*; D018570:Risk Assessment; D012907:Smoking / Q000009:adverse effects*