A history of emphysema conferred a 2.44-fold increased risk of lung cancer (95 confidence interval (CI): 1.64, 3.62 (16 studies)). A history of chronic bronchitis conferred a relative risk of 1.47 (95 CI: 1.29, 1.68 (13 studies)).
Tuberculosis (relative risk 1.48, 95 CI: 1.17, 1.87 (16 studies)) and pneumonia (relative risk 1.57, 95 CI: 1.22, 2.01 (12 studies)) were also associated with lung cancer risk. Among never smokers, elevated risks were observed for emphysema, pneumonia, and tuberculosis.
These results suggest that previous lung diseases influence lung cancer risk independently of tobacco use and that these diseases are important for assessing individual risk.