Mutation status of epidermal growth factor receptor and clinical features of patients with combined small cell lung cancer who received surgical treatment

The mutation status of epidermal growth factor receptor (EGFR) is correlated with the response of tumors to EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC), suggesting its usefulness as a biomarker in NSCLC. The incidence of EGFR mutation in NSCLC is higher in China than in the United States and European countries. There have been some case reports concerning cases of gefitinib-responsive small cell lung cancer (SCLC) with EGFR mutations. However, few large studies concerning the mutation status of SCLC patients have been performed. We detected EGFR mutations in exons 19 and 21 of 40 SCLC patients, three of whom had combined SCLC, from the Zhejiang Cancer Hospital using xTAG technology. Only two patients with combined SCLC had an EGFR mutation in exon 19. To determine the EGFR mutation status and clinical features of combined SCLC, we retrospectively analyzed the clinical features of seven patients with combined SCLC who had undergone surgical treatment in Zhejiang Cancer Hospital between 2007 and 2010. EGFR mutations in exons 19 and 21 were detected using the pyrosequencing assay. Of the seven patients with combined SCLCs, 71.4% were male, 71.4% were heavy smokers, most were over 60 years old and 71.4% of the cases were combined adenocarcinoma. Chemotherapy treatment and tumor stage were correlated with survival time. Of the seven cases, one had a mutation in exon 19 of EGFR in both the conventional SCLC and SCLC combined adenocarcinoma components. Combined SCLC commonly occurs in patients who are heavy smokers, male and over 60 years old, and most of the combined type cases are adenocarcinoma. The treatment of combined SCLC may be applied to cases of conventional SCLC. EGFR mutations may therefore occur in combined SCLCs, especially in SCLC combined adenocarcinoma in China.