Cigarette smoking increases the risk of mortality from liver cancer: A clinical-based cohort and meta-analysis

Background and Aim: Although the influence of cigarette smoking on the incident risk of liver cancer has been determined, the association between smoking and liver cancer mortality remains uncertain. Methods: We searched Pubmed, EmBase, and Web of Science databases to obtain eligible studies. Hazard ratio (HR) value and 95% confidential intervals (CI) were pooled by using a random-effects model, and dose-response analyses were conducted to quantify associations between smoking and mortality from liver cancer. Results: A total of 27 articles involving four million participants from seven countries by retrieval (published 1986-2014) were finally included. Pooled HR values for liver cancer mortality was 1.45 (95% CI: 1.33-1.59), 1.22 (95% CI: 1.11-1.34) and 1.16 (95% CI: 1.01-1.32) for current, former, and ever smokers, respectively, when compared with nonsmokers. The risk increased by 7.1% (95% CI: 1.4-13.2) for per additional 10 cigarettes per day and by 5.2% (95% CI: 0.02-11.2) for per additional 10 pack-years. In our population recruiting 597 patients with liver cancer, smoking status was further identified as a significant determinant factor of tumor size and serum level of gamma-glutamyl transpeptidase, but not a significant prognostic factor. Conclusions: Cigarette smoking, especially current smoking, significantly increased mortality risk from liver cancer.