Association between smoking and environmental tobacco smoke with lung cancer risk: a case–control study in the Fujian Chinese population

Aim To investigate the association between smoking, environmental tobacco smoke (ETS), and lung cancer risk. Methods This case–control study included 1622 newly diagnosed cases of lung cancer and 1622 healthy frequency-, age-, and gender-matched control participants. Epidemiological data were collected by in-person interviews using a standard questionnaire. Results Smoking was a risk factor for lung cancer in men (odds ratio (OR) = 4.486, 95% confidence interval (95%CI) 3.586–5.611). In addition, decreased starting age, increased number of cigarettes smoked per day, duration of smoking, pack–years, and depth of inhalation were all risk factors that met the dose–response relationship ( P < 0.001). The risk of lung cancer was lower among men who had quit smoking for more than 10 years compared to current smokers. Additionally, male smokers with lung squamous cell carcinoma were at a higher risk of lung cancer than male smokers with lung adenocarcinoma. Workplace ETS increased the risk for lung cancer for male nonsmokers (OR = 2.452, 95%CI 1.534–3.920). In contrast, household ETS increased the risk for lung cancer for female nonsmokers (OR = 2.224, 95%CI 1.644–3.009). Approximately 65.93% cases of lung cancer in men could be attributed to smoking, whereas approximately 31.03% cases of lung cancer among nonsmokers could be attributed to ETS. Conclusions Smoking is the main risk factor for lung cancer. Workplace ETS is associated with increased lung cancer risk in male nonsmokers, while household ETS is associated with increased lung cancer risk in nonsmoking women. Thus, smoking and ETS increase the risk of lung cancer and are major public health concerns.