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 long-term 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.