Progression-Free Survival: An Important Prognostic Marker for Long-Term Survival of Small Cell Lung Cancer

Background: Small cell lung cancer (SCLC) is an extremely aggressive tumor with a poor clinical course. Although many efforts have been made to improve patients' survival rates, patients who survive longer than 2 years after chemotherapy are still very rare. We examined the baseline characteristics of patients with long-term survival rates in order to identify the prognostic factors for overall survivals. Methods: A total of 242 patients with cytologically or histologically diagnosed SCLC were enrolled into this study. The patients were categorized into long-and short-term survival groups by using a survival cut-off of 2 years after diagnosis. Cox's analyses were performed to identify the independent factors. Results: The mean patient age was 65.66 years, and 85.5% were males; among the patients, 61 of them (25.2%) survived longer than 2 years. In the multivariate analyses, CRP (hazard ratio [HR], 2.75; 95% confidence interval [CI], 1.25-6.06; p= 0.012), TNM staging (HR, 3.29; 95% CI, 1.59-6.80; p=0.001), and progression-free survival (PFS) (HR, 11.14; 95% CI, 2.98-41.73; p<0.001) were independent prognostic markers for poor survival rates. Conclusion: In addition to other well-known prognostic factors, this study discovered relationships between the longterm survival rates and serum CRP levels, TNM staging, and PFS. In situations with unfavorable conditions, the PFS would be particularly helpful for managing SCLC patients.