Clinical characteristics and prognostic factors of surgically resected combined small cell lung cancer: a retrospective study.

Objectives Small cell lung cancer (SCLC) is the most malignant lung cancer. Some of them are mixed with non-small cell lung cancer(NSCLC, Non SCLC),which are called combined small cell lung cancer (C-SCLC).Due to the difficulty of pathological diagnosis and the complexity of treatment, studies of C-SCLC have just been rising in recent years. This study is to evaluate the clinical and pathologic characteristics of C-SCLC. Methods Stage Ⅰ-Ⅲa C-SCLC patients who received radical R0 surgery between 2009-2018 in Shanghai Chest Hospital were enrolled. Clinical characteristics and prognosis were analyzed. Results Totally 181 patients were included, most of them were small cell combined with large cell neuroendocrine components(SCLC/LCNEC,58.0 %,N = 105),then with adenocarcinoma(SCLC/ADC:13.8 %,N = 25),and finally with squamous cell carcinoma(SCLC/SCC:13.3 %,N = 24).Median DFS and OS of C-SCLC patients underwent radical surgery were 32.5 and 49.7 months.1,3 and 5 years DFS rates of the entire cohort were 68.5 %,32.6 % and 16.0 %,respectively. Patients with SCLC/LCNEC had longer DFS (44.1 m vs. 20.4 m, p = 0.040) and longer OS trend (62.1 m vs. 33.2 m, p = 0.122).Groups of whether tumor invaded the pleura(p = 0.028 and p = 0.050),lymph node stage(p = 0.029 and p = 0.010) and the courses of adjuvant chemotherapy(p = 0.011 and p = 0.001) had statistical differences on DFS and OS. Conclusions SCLC/LCNEC was the most common type of C-SCLC. Patients' DFS and OS were also longer than other combined types. Adjuvant chemotherapy for SCLC is still the main treatment for surgical C-SCLC. Further studies are needed to clarify the clinical characteristics and prognosis of C-SCLC.