Lung Cancer Risk Attributable to Active Smoking in China: A Systematic Review and Meta-Analysis

Objective No consensus exists on the relative risk (RR) of lung cancer (LC) attributable to active smoking in China. This study aimed to evaluate the unified RR of LC attributable to active smoking among the Chinese population.Methods A systematic literature search of seven databases was conducted to identify studies reporting active smoking among smokers versus nonsmokers in China. Primary articles on LC providing risk estimates with their 95% confidence intervals (CIs) for "ever" "former" or "current" smokers from China were selected. Meta-analysis was used to estimate the pooled RR of active smoking.Results Forty-four unique studies were included. Compared with that of nonsmokers, the pooled RR (95% CI) for "ever" "former" and "current" smokers were 3.26 (2.79-3.82), 2.95 (1.71-5.08), and 5.16 (2.58-10.34) among men, 3.18 (2.78-3.63), 2.70 (2.08-3.51), and 4.27 (3.61-5.06) among women, and 2.71 (2.12-3.46), 2.66 (2.45-2.88), and 4.21 (3.25-5.45) in both sexes combined, respectively. Conclusion The RR of LC has remained relatively stable (range, 2-6) over the past four decades in China. Early quitting of smoking could reduce the RR to some extent; however, completely refraining from smoking is the best way to avoid its adverse effects.