When an international group of researchers investigated a possible link between lung cancer risk and concomitant respiratory conditions, they found a significantly increased occurrence of lung cancer in patients with chronic bronchitis, emphysema, and pneumonia. These results did not hold true for concomitant tuberculosis or asthma.
“In our pooled analysis of seven case-control studies involving more than 12,500 cases and 14,900 controls, we found associations between lung cancer and chronic bronchitis, emphysema, and pneumonia, with a greater increased lung cancer risk among subjects with all three of these conditions,” said Ann Olsson, PhD, principal investigator of the study, “Is Previous Respiratory Disease a Risk Factor for Lung Cancer?“, published in the journal American Journal of Respiratory and Critical Care Medicine. Dr. Olsson spoke in a news release from the American Thoracic Society.
The cases came from the SYNERGY project, which pooled information concerning respiratory diseases in patients from Europe and Canada. Five respiratory conditions, in addition to lung cancer, were of interest: chronic bronchitis, emphysema, tuberculosis, pneumonia, and asthma. Chronic bronchitis and pneumonia were the most common, and emphysema was the least common.
Odds ratios were the outcomes for analyses of self-reported respiratory disease, after correcting for study center, age, employment in an occupation with an excess risk of lung cancer, education level, and smoking habits.
Individually, chronic bronchitis in men gave an odds ratio of 1.33, emphysema gave an odds ratio of 1.50, and pneumonia gave an odds ratio of 3.31 when diagnosed two or fewer years (but not more) prior to a lung cancer diagnosis. These odds were enhanced when all three conditions were present.
Rather than demonstrate an associated increased risk, asthma showed an inverse relationship to lung cancer occurrence, and tuberculosis had no association with lung cancer risk.
“The variations in the associations between lung cancer and different patterns of previous respiratory disease that we observed in our study may indicate differences in the underlying etiological mechanisms,” said Dr. Olssen. “Better understanding of these associations may help guide the type and frequency of clinical surveillance needed for patients with each of these diseases.”
Unique to this study was the perspective the researchers took when looking at disease risk. “Associations between various respiratory diseases and lung cancer have been shown in earlier studies, but few of these studies considered multiple respiratory disease simultaneously,” said Dr. Olsson. The large sample size analyzed suggests that patients with chronic bronchitis and emphysema have an increased risk for developing lung cancer.