© 2007 American Thoracic Society
A Major Cause of Death in COPD and Risk Factors for Lung Cancer—a Dilemma or a Mistake?To the Editor:We believe that the cohort examined by Parimon and colleagues as reported in their article (1) was appropriate to establish an association between the use of inhaled steroids and the decrease in incidence of lung cancer in patients with chronic obstructive pulmonary disease (COPD) . However, I also strongly believe that the cohort should have been followed for a longer period, as 26 months is too short a time to study a disease that takes years to develop. I have a slight disagreement with the statement "the most common cause of death among subjects with chronic obstructive pulmonary disease (COPD) is lung cancer." The Lung Health study cited by Parimon and coworkers clearly stated lung cancer to be the most common cause of death in COPD, but among the mild to moderate subgroup (2). In yet another mortality study by Sin and coworkers, lung cancer was the dominant cause of mortality among asymptomatic patients with COPD. In more advanced COPD (<60% FEV1), however, respiratory failure was the predominant cause (3). Also mentioned by Sin and coworkers were several other studies indicating respiratory failure as overall the most common cause in the subgroups combined (3). Hence, it would be premature to decide on the most common cause of mortality until more conclusive evidence is available. In addition, the statement "Chronic obstructive pulmonary disease is a major risk factor for lung cancer" is controversial. Smoking is the major risk factor for lung cancer, whereas the presence of COPD is an important risk factor among the smoking subgroup (4, 5). Whether the inflammatory and carcinogenic effects of primary substances in tobacco smoke or the COPD disease process itself leads to cancer needs to be explored before this statement can be confirmed. The editorial in the same issue of the AJRCCM by Miller and Keith highlighted important shortcomings of this article regarding compliance to inhaled corticosteroids in the subjects, which probably led to inconclusive results (6). Finally, the statement "delivery of inflammatory agents to the lung was associated with a decreased risk of developing lung cancer" proves that this article was not adequately reviewed. Even though this is a nonscientific error, it affects the validity and reliability of the text. We recommend that the editorial board of the journal review articles with extreme caution before publishing as a mistake like this can mislead many students/professionals, particularly those linked with patient care.
The Aga Khan University, Karachi, Pakistan FOOTNOTES Conflict of Interest Statement: None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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