Prognostic factors in small cell lung cancer: a new prognostic index in Korean patients

The aims of this study were to identify prognostic factors for overall survival (OS) in patients with small cell lung cancer (SCLC) and to construct a prognostic index on the basis of their expected OS. Long-term survivors were also given special attention.

We retrospectively analyzed 295 patients diagnosed with SCLC from January 2002 to September 2007 at the Severance Hospital, Seoul, Republic of Korea. Patient history was reviewed regarding both clinical and tumor-related markers, and treatment-related factors were also evaluated.

There were 131 (44.4%) patients with limited disease (LD) and 164 (55.6%) with extensive disease (ED). Median follow-up lasted 9.4 months. Objective response to chemotherapy was 66.8%. The median survival time (MST) was 11.2 months in all patients, 20.4 months in LD patients, and 7.7 months in ED patients. The median progression-free survival was 9.4 months. Independent prognostic factors for overall survival (OS) were extent of disease, performance status, and CYFRA 21-1 level. We classified all patients into four groups based on the results of multivariate analysis using classification and regression tree analysis. Median survival times were 22.7, 13.7, 8.5, and 3.2 months, respectively. A total of 51 (17.3%) patients from the entire study population were evaluated for long-term survival, which was defined as survival >2 years. Their MST was 43.1 months, and extent of disease, performance status, and CYFRA 21-1 were independent prognostic factors for long-term survival.

We confirmed the well-known prognosticators, disease extent and performance status, in our patients, but further identified CYFRA 21-1 as independent prognostic factor. A prognostic index was constructed to create four classifications of SCLC considering these variables.