Peripheral-type small cell lung cancer is associated with better survival and higher frequency of interstitial lung disease.

Objectives: Small cell lung cancer (SCLC) can be subgrouped into central and peripheral types according to the location of the primary lesion. However, the clinical differences between these two types remain unclear. This study compared their clinical features.

Materials And Methods: Data on 231 patients with pathologically diagnosed SCLC were retrospectively subgrouped into central or peripheral types. Progression-free survival (PFS), overall survival (OS), treatments, responses to first-line therapy, and frequency of interstitial lung disease (ILD) were compared between the two groups.

Results: Of the 231 patients, 101 (44%) had central-type and 130 (56%) had peripheral-type SCLC. Peripheral-type SCLC was associated with a better performance status, higher frequency of ILD, and higher rate of limited disease stage. Patients with peripheral-type SCLC had a significantly longer OS than did those with central-type SCLC (median, 502 vs 370days, respectively; p=0.0186). Tumor location was not associated with PFS. PFS was poorer in patients with than without ILD (median, 143 vs 213days, respectively; p=0.0038), as was OS (median, 245 vs 545days, respectively; p=0.0014). Among patients without ILD, OS was longer in those with peripheral- than central-type tumors (median, 662 vs 421days, respectively; p=0.0074). Surgical resection was more often chosen for peripheral-type tumors, and this was one reason for the prolonged survival. There was no difference in the response to chemotherapy and/or radiotherapy between central- and peripheral-type SCLC. Multivariate analysis by a Cox proportional hazards model showed that male sex, a poor performance status, extensive disease, the presence of ILD, an elevated serum neuron-specific enolase concentration, and central-type SCLC were poor prognostic factors for OS.

Conclusion: Peripheral-type SCLC is associated with better OS and a higher frequency of ILD than is central-type SCLC. The presence of ILD is a poor prognostic factor for both PFS and OS.