Small‐cell lung cancer from the peripheral lung is frequently accompanied by emphysema and interstitial lung disease in the background

Background It has long been thought that small-cell lung cancer (SCLC) is a central type of tumor that is located in the proximal bronchi and the mediastinum. However, several studies reported that SCLC exhibited several types of spread pattern on computed tomography (CT). The aim of this study is to investigate the relationship between CT images and clinical characteristics in patients with SCLC. Methods We retrospectively reviewed the CT images of 92 SCLC patients and classified them into six types of spreading patterns: central, peripheral, lymphangitic spread (LYM), pleural dissemination (PLE), lobar replacement (LOB), and air-space consolidation (AC). We also evaluated the correlation between primary tumor location and the clinical characteristics of patients. Results The most common type of imaging pattern was peripheral (n = 40, 44%), with the next most common type being central (n = 27, 29%). Atypical types of SCLC, such as LYM (n = 2, 2%), PLE (n = 4, 4%), LOB (n = 8, 9%), and AC (n = 11, 12%), were also recognized in our study. The prevalence of emphysema and interstitial lung disease (ILD) was significantly higher in the peripheral type than in the central type (p = 0.0056 and p = 0.0403, respectively). Meanwhile, no survival difference was seen between the central type and the peripheral type (median months 17.9 vs. 21.9, respectively, p = 0.720). Conclusions The peripheral type of tumor was correlated with higher prevalence of emphysema and ILD in SCLC. Our result suggests different mechanisms of development and tumor characteristics according to tumor location.