Background: There has been conflicting evidence about possible associations between nonmalignant respiratory conditions (NMRCs) and subsequent risk of lung cancer. Determination of whether or not there is such an association has potential importance for managing NMRCs, for screening of lung cancer, and for understanding mechanisms of carcinogenesis.
Methods: A hospital-based, case-control study involving interviews with 226 female nonsmoking lung cancer patients and 279 matching population controls was conducted in Shenyang, Northeast China, between January 2004 and December 2007. A standardized interview collected information on a variety of potential risk factors, including a history of physician-diagnosed NMRCs (pulmonary tuberculosis, chronic bronchitis, emphysema, asthma, and bronchiectasis), and age/year in which each condition was first diagnosed. Multivariate logistic regression analyses were applied to assess the associations between NMRCs and subsequent lung cancer risk.
Results: Compared with those without, subjects with a history of NMRC experience greater risk of lung cancer (OR=2.0, 95% CI 1.2-3.4), particularly following a diagnosis of pulmonary tuberculosis (OR=4.7, 95% CI 1.6-13.2). The results from subgroup analysis, when limited to small cell lung cancer, showed a 6.2-fold increase in lung cancer risk among asthmatics (95% CI 1.5-25.8). However, there was no evidence of a significant association between chronic bronchitis and lung cancer.
Conclusions: This study strengthens the evidence linking NMRCs, especially pulmonary tuberculosis, to lung cancer even in lifelong nonsmoking women.