Abstract
PURPOSE: Currently, systemic chemotherapy combined with thoracic radiation is the standard treatment for patients with small-cell lung cancer (SCLC). However, the treatment of early stage SCLC remains controversial. This study evaluated the survival outcomes of surgical treatments and the effect of adjuvant chemotherapy and radiotherapy on lung cancer-specific survival (LCSS) in patients with early stage SCLC. METHODS: Using the Surveillance, Epidemiology, and End Results registry, we identified 2,453 patients with early stage SCLC (1,295 women and 1,158 men) who had complete clinical information between 2004 and 2015. The Kaplan-Meier analysis was used to determine the propensity score based on the characteristics of patients with early stage SCLC. LCSS was compared between patients treated with surgery and non-surgery after adjusting, stratifying, or matching patients with early stage SCLC. In addition, we compared the effects of chemotherapy and radiotherapy on LCSS in patients with early stage SCLC. RESULTS: Overall, 687 (28.0%) and 1,766 (72.0%) patients with early stage SCLC did and did not undergo surgery, respectively. Kaplan-Meier analysis demonstrated a statistically significant difference in survival curves between the surgery and non-surgery groups (log-rank p<0.001). Compared with the non-surgery group, the LCSS of the surgery group was better (hazard ratio [HR]:0.494, 95% confidence interval [CI]:0.415-0.587, p<0.001) in patients with early stage SCLC when using a Cox model for multivariate analysis. There was no statistically significant difference (p=0.847) in LCSS between patients with early stage SCLC with and without chemotherapy in the multivariate analysis. Radiotherapy had favorable effects on LCSS (HR: 0.579, 95% CI: 0.500-0.671, p<0.001) in patients with early stage SCLC using multivariate analysis. CONCLUSIONS: Our study results suggest that LCSS conferred by surgery was higher than that conferred by non-surgery and that radiotherapy is associated with better survival in patients with early stage SCLC. This study findings should be confirmed in prospective studies.