A systematic review of cohort studies on the association of smoking with all-cause and lung cancer mortality in China

Abstract

Background Smoking is a well-established causal risk factor of premature death. The prevalence of smoking has been estimated to be more than 50% in Chinese men. However, previous reviews of the association between smoking and mortality from all-causes and lung cancer were mainly relied on developed countries. The current systematic review of cohort studies aims at summarizing the existing studies on the association of smoking with all-cause and lung cancer mortality in China.

Methods Articles published from 1980 to 2014were searched systematically in databases including PubMed, EMBASE, China National Knowledge Infrastructure (CNKI) and Google scholar. Main results of all studies were extracted and summarized.

Results A total of 14 cohort studies examining the association of smoking with all-cause and lung cancer mortality in Chinese populations were identified. Compared with never smoking, current smoking was associated with higher risks of all-cause and lung cancer mortality in all studies. The relative risks (RR) for current smokers were from 1.20 to 2.29 for all-cause mortality and from 2.44 to 9.40 for lung cancer mortality. Former smokers also showed higher RRs for all-cause mortality (RR=1.20-1.48) and for lung cancer mortality (RR=2.06-6.50) compared with never smokers. Furthermore, dose-response associations of increasing smoking categories with all-cause mortality and lung cancer mortality were observed in most of the studies.

Conclusions The risk estimates for all-cause and lung cancer mortality from smoking in China were lower than those from the western countries suggesting that the tobacco epidemic is at an early stage in China. Further large cohort studies giving updated risk estimates are warranted for advocating stringent tobacco control policies in China.