Basic fibroblast growth factor (bFGF) is a secreted multifunctional cytokine and a potent stimulator of angiogenesis. We measured bFGF concentrations from serum samples taken from 103 patients with small cell lung cancer at the time of diagnosis. Serum concentration of bFGF (S-bFGF) ranged from undetectable to 54 pg/ml (median, 6 pg/ml). S-bFGF was not associated with age, sex, performance status, or stage. A high pretreatment S-bFGF was associated with poor overall survival. The 1- and 2-year survival rates of the patients within the highest quartile of S-bFGF (>or=17 pg/ml) were only 26% and 11%, respectively, in contrast to the 49% and 20% 1- and 2-year survival rates of those patients with S-bFGF or=17 pg/ml) were as low as 16% and 5%, respectively (P = 0.0026). Similarly, in the multivariate model of survival analysis, patients with both extensive-stage disease and a high S-bFGF (>or=17 pg/ml) were found to have a particularly poor prognosis (relative risk of death, 2.1; 95% confidence interval, 1.2-3.6; P = 0.0057). We conclude that a high S-bFGF at diagnosis is associated with poor outcome in small cell lung cancer, possibly reflecting active angiogenesis and rapid tumor growth, and may complement prognostic information obtained by staging.