Clinical Outcomes and Prognostic Factors in Limited-Stage Small Cell Lung Cancer Patients Treated with Intensive Modified Radiation Therapy

Abstract

To investigate the clinical effect of combined modality treatment and examine the prognostic factors for overall survival (OS) in limited-stage small cell lung cancer (LS-SCLC) on the base of intensive modified radiotherapy (IMRT). A retrospective analysis was performed on the clinical data of 484 LS-SCLC patients treated with chemotherapy and IMRT in our centre from August 2006 to May 2014. All patients were primarily managed with concurrent or sequential chemoradiotherapy, followed by prophylactic cranial irradiation (PCI) in patients with complete or partial response. IMRT was adopted in all patients with a median radiation dose 60Gy (2Gy once daily over 6 weeks). Kaplan-Meier method was used for survival analysis, and Log-rank test and Cox regression were used for univariate and multivariate analysis of prognostic factors. Follow-up rate was 93%. The median survival time(MST) was 23.8 months (95%CI 20.3-27.4), and the 2-,3-, and 5-year OS were 48.7%,39.8%, and 28.6%, respectively. The median progression-free survival time(PFS) was 14.1 months (95%CI 12.6-15.5), and the 2-,3-, and 5-year PFS were 34.4%, 30.5%, and 28.3%, respectively. The acute toxicity after chemotherapy and thoracic IMRT was tolerable. The acute toxicities included grade ≥3 hematological toxicity, grade ≥2 radiation esophagitis and grade ≥2 pneumonitis, which occurred in 26.9%, 24.8%, and 18.4% of all patients. The rates of CR, PR, SD, PD after thoracic radiation were 15.5%, 69.0%, 5.6%, 7.0%, respectively. Response information of 14 patients were lost and objective response rate was 84.5%. The univariate analysis showed that age, smoking history, TNM stage, PCI and the number of induction chemotherapy cycles were significant prognostic factors for OS of LS-SCLC (P=0.006, 0.001, 0.047, <0.001,0.046). The multivariate analysis showed that smoking history and PCI were independent factors affecting the prognosis for the LS-SCLC patients (P=0.001, <0.001). Combined chemotherapy and thoracic IMRT achieved satisfactory clinical outcomes and mild toxicity in LS-SCLC. Smoking history and PCI are independent prognostic factors for OS of LS-SCLC.