Prevalence of underlying lung disease in smokers with epidermal growth factor receptor-mutant lung cancer

The prevalence of underlying lung diseases, such as emphysema and interstitial lung disease in smokers with epidermal growth factor receptor (EGFR)-mutant lung cancer remains unclear. This study aimed to clarify the correlation between the EGFR mutation status and the prevalence of underlying lung disease in smokers with lung cancer. A total of 88 consecutive smokers with non-small cell or non-squamous cell lung cancer who underwent surgical resection at our hospital from January 2007 through December 2010 were included in this study. The patients were divided into two groups on the basis of the EGFR mutation status: the mutation-positive group (n=19) and the wild-type group (n=69). The results of radiographic assessment via computed tomography (CT) and pulmonary function analysis were compared between the two groups. In the radiological evaluation, CT images at three levels were evaluated by two reviewers. Radiographic assessment revealed that the mutation-positive group tended to have milder emphysematous changes and a lower prevalence of interstitial changes compared with the wild-type group (P=0.13, 0.06). When the analysis was limited to the ipsilateral lung at the nearest CT level to the tumor, emphysematous changes were found to be less common in the mutation-positive group (P=0.02). The prevalence of the emphysematous and/or interstitial changes in the ipsilateral lung at the nearest CT level to the tumor was lower in the mutation-positive group compared to the wild-type group (P=0.005). In the pulmonary function test, the results were comparable between the two groups. In conclusion, according to our results, EGFR-mutant lung cancer was commonly observed in the areas where emphysematous and interstitial changes were absent. EGFR-mutant lung cancer may develop in radiographically normal areas of the lungs, even in smokers. It would be of importance to evaluate the EGFR mutation status in patients with no emphysematous or interstitial changes in the ipsilateral lung near the tumor, regardless of their smoking history. These results should be confirmed in a future prospective study.