Effect of histological subtype and treatment modalities on T1–2 N0–1 small cell lung cancer: A population‐based study

Abstract

BACKGROUND: Combined small cell lung cancer (C-SCLC) is rare and its clinical features, appropriate treatment, and prognosis are poorly understood. Reports conflict over the prognosis of C-SCLCs compared to pure small cell lung cancer. METHODS: The records of patients diagnosed with primary SCLC from 1988 to 2014 were extracted from the Surveillance, Epidemiology, and End Results database. The general features of C-SCLCs were compared to those of SCLCs. T1-2 N0-1 data was extracted and the effects of the histological subtype, treatment modality, and other prognostic factors on lung cancer-specific survival (CSS) was analyzed in a 3:1 matched dataset. Analysis was performed using the 8th edition tumor node metastasis staging system and previous staging systems adjunctively. RESULTS: C-SCLCs comprised 1.5% of all SCLCs (1486/98 667); 184 cases of C-SCLCs and 2681 cases of non-combined SCLCs (NC-SCLCs) were included in this study. C-SCLCs were more likely to be of a higher grade and to occur in the upper lobe than NC-SCLCs. Before matching, C-SCLCs showed better CSS (hazard ratio 0.69; P < 0.001). However, stratified Cox proportional hazards analysis in the matched dataset revealed that only treatment modality and age at diagnosis were associated with CSS; the histological subtype had no effect on survival. Of all treatment modalities, surgery with chemoradiation showed the best CSS in T1-2 N0-1 SCLC. CONCLUSION: In early SCLC, surgery with chemoradiation shows the best CSS. C-SCLC patients might benefit more from multimodal treatments, including surgery, than SCLC patients.