Abstract

Over the years, many studies have attempted to establish a link between tobacco smoking and an increased risk of nasopharyngeal carcinoma (NPC), but their results have been inconsistent. To clarify this link, we first conducted a comprehensive meta-analysis to integrate the findings of epidemiologic studies from the last half-century. The methodology used for this study followed the checklist proposed by the Meta-analysis of Observa-tional Studies in Epidemiology (MOOSE) Group. Pooled risk estimates were generated using a random-effects model. Twenty-eight case-control studies and 4 cohort studies involving a total of 10,274 NPC cases and 415,266 comparison subjects were included. A substantial effect of smoking on the risk of NPC was identified in this study. The results showed that ever smokers had a 60 % greater risk of developing the disease than never smokers (95% confidence interval: 1.38, 1.87); this was a robust dose-dependent association. More importantly, stronger associ-ations were observed in low-risk populations and among persons with the predominant histological type of differ-entiated NPC than in high-risk populations and persons with an undifferentiated type; the odds ratios were 1.76 and 2.20, respectively, versus 1.29 and 1.27. In this comprehensive meta-analysis, well-established statistical evi-dence was provided about the role of tobacco smoking in the etiology of NPC. case-control studies; cohort studies; meta-analysis; nasopharyngeal carcinoma; odds ratio; tobacco smoking Abbreviations: CI, confidence interval; NOS, Newcastle-Ottawa Scale; NPC, nasopharyngeal carcinoma; OR, odds ratio.