Guan et al. BMC Cancer 2010, 10:431 http://www.biomedcentral.com/1471-2407/10/431 Page 6 of 9 Figure 3 Overall survival curves by genotypes of VEGF gene. The P values were obtained from the Cox model with adjustment for age, sex, smoking status, tumor histology, KPS score, tumor stage, use of chemotherapy and radiotherapy dose.