The investigators classified qualitative variables according to clinical practice. Age included less than 60 years, 61-66 years, and more than 67 years. The primary tumor location included left-sided and right-sided. The anatomic sites included lower and others. The smoking status included never smoker and ever smoker. The forms of performance status according to the Eastern Cooperative Oncology Group scale (ECOG PS) were ECOG ≤ 2, and ECOG ≥ 3. Five groups were formed according to clinical T stage (T0-1, T2, T3, T4, and T stage that could not be evaluated). Three groups were formed according to clinical N stage (N0-1, N2-3, and N stage that could not be evaluated). Some stages were unevaluated, on account of a portion of non-measurable tumor size and lymph node. Three groups were formed according to clinical M stage (M0, Ma-b, Mc). Four groups were formed according to clinical TNM stage (Ⅰ-Ⅱ, Ⅲ, Ⅳ and TNM stage that could not be evaluated). The common metastatic sites(brain, liver, and bone) of tumor was divided into none and yes. The hematologic markers (serum natrium , lactate dehydrogenase, carcinoembryonic antigen, neuron-specific enolase, cytokeratin 19 fragment, and pro-gastrin-releasing peptide) were divided into normal and abnormal. The above information was collected before treatment. The RECIST version 1.0 was used to assess tumor responses after initial imaging studies of commencing chemotherapy. Initial chemotherapy response is the first imaging examination of SCLC patient after starting chemotherapy. Six groups were formed according to initial response to chemotherapy (CR, PR, SD, PD, response that could not be evaluated, and no chemotherapy). Other treatments (radiotherapy, surgery, targeted therapy, immunotherapy, Interventional therapy, and whole-brain prophylactic cranial irradiation) was classified none and yes.
In this retrospective study, patients diagnosed with SCLC between January 2011 to September 2022 were identified from database of the Second Hospital of Shandong University. Following inclusion criteria should be met: (1) Had histologically or cytologically confirmed newly diagnosed SCLC; (2) No cancer treatment has been done before; (3) Complete clinical, laboratory, imaging, treatment data and follow-up information. The exclusion criteria included: Patients without complete records for pathological information, complete epidemiology and other key clinical information.