History of lung disease and risk of lung cancer in a population with high household fuel combustion exposures in rural China.

History of chronic lung diseases and household coal use for heating and cooking are established risk factors of lung cancer; however, few studies have been able to explore these risk factors simultaneously. Xuanwei, China, has some of the highest rates of lung cancer in China and most residents experience substantial in-home coal smoke exposures. Using a population-based case-control study of 498 lung cancer cases and 498 age-matched controls, we evaluated the risk of lung cancer in relation to coal smoke exposure and history of chronic lung diseases, including chronic obstructive pulmonary disease (COPD), asthma, tuberculosis (TB), chronic bronchitis, and emphysema. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by conditional logistic regression adjusting for potential confounders. We observed an increased risk of lung cancer with history of any chronic lung disease among males (OR = 14.2; 95%CI = 4.3-46.9), females (OR = 2.6; 95%CI = 1.1-6.3), smokers (OR = 12.7; 95%CI = 3.5-45.8), and nonsmokers (OR = 2.6; 95%CI = 1.1-6.4). Specifically, TB (OR = 83.7; 95%CI = 11.0-634.7), COPD (OR = 3.2; 95%CI = 1.7-6.0), and emphysema and chronic bronchitis (OR = 3.3; 95%CI = 1.7-6.4) were associated with increased risks. These findings suggest that history of chronic lung diseases may also increase risk of lung cancer in populations with indoor coal smoke exposures.