21152 Background: Small cell lung cancer (SCLC) has a rapid growth rate, and is characterized by early metastases. Tumor growth is dependent on angiogenesis. Vascular endothelial growth factor (VEGF) is an important regulator of angiogenesis. Whether surveillance of pre and post treatment serum VEGF and its receptors Flt-1 and Kdr levels in SCLC patients have impact on clinical outcome is unknown. Methods: From February 2001- January 2003, 39 consecutive patients (34 male, 5 female) with histologically proven SCLC were enrolled into the study. The patients were staged as limited and extensive according to the Veterans Administration Lung Group (VALSG). Pre treatment (n:39) and post treatment (n:25) serum samples of the same patients after 3 months of treatment were collected. The levels of VEGF and its receptors Flt-1 and kdr are measured in the serum by quantitative sandwich enzyme immunoassay technique. Statistical analysis was performed using the SPSS 10.0 pocket program. Results: The median pretreatment serum VEGF, Flt-1, and Kdr levels were 1,200 pg/ml (range, 1,414.3±956.2 pg/ml), 85 pg/ml (range, 97.8±70.7 pg/ml), and 11,550 pg/ml (range, 14,481±6,267 pg/ml) respectively. The pretreatment serum VEGF, Flt-1, and Kdr concentrations were not different in limited and extensive stages. We detected a poor but positive correlation between VEGF and Kdr (r=0.46, p=0.003). Pretreatment low serum VEGF value (<728.5 pg/ml) and good response to treatment were found as good prognostic factors in multivariate analysis. Surveillance of serum VEGF and Flt-1, Kdr values did not correlate with clinical parameters. Conclusions: Serum VEGF was found to be a significant and independent prognostic factor in SCLC patients. We showed a limited association between serum levels of VEGF and Kdr. Whether the levels of serum VEGF and its receptors Flt-1 and kdr have value in detecting treatment modalities of SCLC needs further studies. No significant financial relationships to disclose.