Tobacco smoking and oral cancer: a meta-analysis.
BACKGROUND
Several epidemiological studies suggest that tobacco smoking increases the risk of oral cancer. No systematic review, however, has been reported to examine how consistent the evidence is across the studies. We undertook a meta-analysis of epidemiological studies investigating the magnitude relationship between tobacco smoking and oral cancer.


METHODS
Primary studies were identified through a computerized literature search of Medline. Articles abstracted were all epidemiological studies published as original articles in English during 1990-2007 provided the summary estimates of odds ratios (OR) of tobacco smoking for oral cancer compared to that of non-smokers. A total of 15 case-control studies were used for this meta-analysis. Summary of OR was calculated based on random effects model.


RESULTS
The combined odds ratio for tobacco smoking related to oral cancer was 4.65 (95%CI, 3.19-6.77). Also, the highest combined odds ratio was belong to America continents (OR= 7.65; 95%CI, 5.11-11.45) and the lowest was in Asia (OR= 1.88; 95%CI, 0.95-3.71). There was heterogeneity in the pooled OR estimate across the studies.


CONCLUSIONS
Our results clearly indicate that tobacco smokers are at increased risk of oral cancer. The cancer risk can be reduced by controlling of tobacco smoking in different countries.
Dept. of Biostatistics & Epidemiology, Hamadan University of Medical sciences, Iran.
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