Studies have suggested a relationship between previous respiratory diseases and a lung cancer diagnosis. Most of this research has been conducted in Asian populations and does not account for the high level of co-occurrence that has been observed among different respiratory diseases. To better understand the relationship between multiple previous respiratory diseases and lung cancer risk, Paolo Boffetta, MD, MPH, and colleagues pooled data from a consortium of seven case-control studies as part of the SYNERGY project, which provided detailed information on smoking habits in European and North American populations.
Data on five previous respiratory diseases—chronic bronchitis, emphysema, tuberculosis, pneumonia, and asthma—were collected by self-report for the study, which was published in the American Journal of Respiratory and Critical Care Medicine. Analyses were stratified by gender and adjusted for study center, age, employment in an occupation with an excess risk of lung cancer, level of education, smoking status, cigarette pack-years, and time since quitting smoking.
According to the results, patients with chronic bronchitis, emphysema, and pneumonia were at higher risk of lung cancer when compared with those who had no previous respiratory disease diagnoses. In men, chronic bronchitis and emphysema were associated with odds ratios (ORs) of 1.33 and 1.50, respectively, for lung cancer. Men who were diagnosed with pneumonia 2 or fewer years prior to lung cancer were also at greater risk of lung cancer (OR, 3.31), but this correlation leveled off when a pneumonia diagnosis was made after the 2-year threshold.
Patients with co-occurring chronic bronchitis, emphysema, and pneumonia had a higher risk of lung cancer than those who had any of these conditions alone. Patients who had diagnosed asthma for 5 or more years were more likely to develop lung cancer than those who received a diagnosis over less time. No association was found between tuberculosis and lung cancer. The authors also noted that the association between chronic bronchitis and lung cancer was negated among patients with comorbid asthma or tuberculosis.
“Clinicians should keep in mind that a history of chronic respiratory disease can increase risks for developing lung cancer and should serve as a trigger to screen for the cancer,” says Dr. Boffetta. “This risk goes beyond environmental exposures. Current guidelines for lung cancer screening are based on age and smoking history. Future analyses are needed to further confirm our findings and gain a better understanding of these associations. Ideally, we should seek to determine if a history of COPD, bronchitis, or emphysema can help us determine if these patients are at particularly high risk for lung cancer and should subsequently undergo screening and surveillance for the cancer.”