Several common respiratory diseases are tied to an increased risk of lung cancer, according to a study published online in the American Journal of Respiratory and Critical Care Medicine.
Rachel Denholm, Ph.D., from the International Agency for Research on Cancer in Lyon, France, and colleagues from the SYNERGY project pooled information on previous respiratory diseases from seven case-control studies (12,739 cases and 14,945 controls) conducted in Europe and Canada in order to assess the relationship between individual diseases. Adjustments were made for co-occurring conditions and patterns of respiratory disease diagnoses and lung cancer.
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The researchers found that chronic bronchitis and emphysema were positively associated with lung cancer, after accounting for other respiratory diseases and smoking (for example, in men: odds ratios, 1.33 and 1.50, respectively).
For lung cancer and pneumonia diagnosed no more than two years prior, there was a positive relationship to lung cancer (odds ratio, 3.31 for men), but not for longer periods of time. There was a stronger positive association with lung cancer between co-occurrence of chronic bronchitis, emphysema, and pneumonia, compared to individual conditions.
There was an inverse association noted between asthma and lung cancer, with the association even stronger with an asthma diagnosis at least five years prior to lung cancer versus shorter time frames.
“Findings from this large international case-control consortium indicate that after accounting for co-occurring respiratory diseases, chronic bronchitis and emphysema continue to have a positive association with lung cancer,” the authors write.