Chronic obstructive pulmonary disease (COPD) and lung cancer are two of the most important smoking-related diseases worldwide, with a huge combined mortality burden. Many consider the presence of COPD itself to be an independent risk factor for lung cancer. Others argue that smoking contributes to both COPD and lung cancer. A study published in the January 2013 issue of the International Association for the Study of Lung Cancer's (IASLC) Journal of Thoracic Oncology, concludes that COPD is not an independent risk factor for lung cancer.

Researchers from the University of Nottingham looked at patients with lung cancer between January 2000 and July 2009 from The Health Improvement Network, a general practice database, in the United Kingdom.

Researchers, "found evidence of a strong association between COPD and lung cancer, but this was largely explained by the effect of smoking and is most apparent in recently diagnosed cases of COPD, suggesting a strong element of ascertainment bias."

They go on to say that there is "an extremely strong unadjusted relationship between both COPD and pneumonia and lung cancer in the 6 months immediately before lung cancer diagnosis. This is useful in a clinical context, highlighting the need to consider a diagnosis of lung cancer when making new diagnoses of COPD or pneumonia."

The researchers support the current recommendations of the American Thoracic Society and the U.K. National Institute for Health Research, that all patients should have a chest radiograph looking for evidence of lung cancer at the time of COPD diagnosis.

The lead author of this work is Dr. Helen Powell. Co-authors include IASLC member Dr. David Baldwin.