Original Research with FEVj% < 40% of predicted, is predictive of lung cancer independent of age, sex, and smoking historyA�as characterized by pack-years. However, the association between lung cancer and radiographic evidence of emphysema, as quantified by automatedA�CT scan analysis, was not statistically significant forA�any degree of severity of emphysema.
Our study confirms numerous reports suggesting that airflow obstruction is an independent risk factorA�for lung cancer. Several potential explanationsA�have been suggested to explain this phenomenon,A�including impaired ciliary clearance in areas of smallA�airway inflammation with pooling of particles andA�prolonged exposure to inhaled carcinogens Accutane Canada, as well asA�shared pathogenic mechanisms between COPD andA�lung cancer. The role of chronic airway inflammationA�induced by cigarette smoke is an active area of research.A�Several pathways, such as the nuclear factor-???� pathway, have been found to be activated by cigaretteA�smoke and are implicated in both local inflammationA�and tumorigenesis. Reactive oxygen species are directA�products of lung inflammation and promote DNAA�alterations that may ultimately lead to lung cancer. The association of other pulmonary inflammatoryA�conditions, such as TB, sarcoidosis, and pulmonaryA�fibrosis with lung cancer, supports this hypothesis. Smoking histories are, however, notoriously unreliable, and it is possible that residual confounding variables, such as smoking or other potential exposures,A�were not adjusted for in these studies, which couldA�have biased their results.
In our study, the degree of radiographic evidence of emphysema was not found to be an independentA�risk factor for lung cancer, in contradiction to theA�findings of two recently published cohort studies. The major difference in these conflicting reports isA�that our methodology for quantifying emphysema wasA�automated and by definition blinded and reproducible. We confirm the findings of the previous study using an improved methodology for automated emphysema quantitation, increasing the power considerablyA�by including a significantly increased number ofA�cases (64 vs 24).