Guan et al. BMC Cancer 2010, 10:431 http://www.biomedcentral.com/1471-2407/10/431 Table 1 Characteristics of the study population (n = 124) and overall survival Characteristics No. of Patients (%) No. of Deaths (%)* P† Age 0.456 MST (95% CI, month) ≤ 60 years > 60 years Gender Female Male Smoke Ever Never Pack -year ≤ 40 > 40 Histology Adenocarcinoma Squamous cell Others KPS 90-100 80 < 80 Stage IIIa IIIb Chemotherapy Yes No Radiotherapy dose < 70Gy ≥ 70Gy 55 (44.4) 69 (56.6) 57 (46.0) 67 (54.0) 114 (91.9) 10 (8.1) 60 (48.4) 64 (51.6) 40 (32.3) 38 (31.6) 46 (37.1) 38 (30.7) 67 (54.0) 19 (15.3) 52 (41.9) 72 (58.1) 112 (90.3) 12 (9.7) 59 (47.6) 65 (52.4) 39 (70.9) 53 (76.8) 39 (68.4) 53 (79.1) 85 (74.6) 7 (70.0) 46 (75.0) 46 (73.0) 31 (77.5) 28 (73.7) 33 (71.7) 24 (66.2) 53 (79.1) 15 (79.0) 34 (65.4) 58 (80.6) 85 (75.9) 7 (58.3) 46 (78.0) 46 (70.8) 0.175 0.752 0.542 0.828 0.175 0.057 0.186 0.360 21.0 (13.0-32.0) 18.0 (13.0-26.0) 26.0 (17.0-38.0) 17.0 (12.0-22.0) 20.0 (16.0-26.0) 16.0 (11.0-18.0) 19.0 (14.0-29.0) 20.0 (13.0-29.0) 20.0 (17.0-31.0) 16.0 (12.0-25.0) 24.0 (13.0-36.0) 22.0 (16.0-39.0) 20.0 (14.0-27.0) 13.0 (8.0-29.0) 20.0 (16.0-39.0) 17.0 (13.0-23.0) 20.0 (16.0-26.0) 17.0 (11.0-44.0) 21.0 (16.0-33.0) 17.0 (12.0-24.0) Page 3 of 9 P‡ 0.468 0.046 0.679 0.861 0.632 0.067 0.088 0.766 0.857 Abbreviations: MST, median survival time. * Percentage of deaths in each stratum. † Chi -square test for difference in the distribution of deaths. ‡ Log-rank test for survival time in the univariate analysis. performed the chi-square test and univariate analysis of Log-rank test for the relationship of death number and OS with clinicopathologic characteristics. We did not find any significant difference in the death distribution by different clinicopathologic characteristics. However, gender seemed to be a confounding factor of OS (MST: 17 months of male vs. 26 months of female, P = 0.046) (Figure 1A), whereas age, smoking status, pack-year, his- tology, application of chemotherapy, and radiation dose did not. Notably, Karnofsky’s performance scores (KPS) and clinical stage showed a marginally significant asso- ciation with OS (P = 0.067 and P = 0.088) (Figure 1B and 1C), suggesting they might be additional confound- ing factors required for control. VEGF genotypes and NSCLC survival The representative PCR-based restriction analyses for the VEGF -460 T > C, -634 G > C, and +936 C > T polymorphisms were shown in Figure 2. The genotype distributions of the three VEGF SNPs and the associa- tion with OS are summarized in Table 2. In all patient, the -460 CT genotype (n = 67) was associated with a significantly increased OS (crude hazard ratio [HR] = 0.60; 95% confidence interval [CI], 0.37-0.95, P = 0.031), compared with the VEGF -460 TT genotype (n = 33). After a multivariate adjustment with age, sex, smoking status, tumor histology, KPS score, tumor stage, history of chemotherapy, and radiation dose, the HR remained statistically significant (adjusted HR = 0.56; 95% CI, 0.34-0.90, P = 0.018; Table 2). Although the homozy- gous CC genotype showed a tendency favoring increased OS, there was no statistical significance, probably because of a reduced detecting power resulting from small sample size (n = 24). Therefore, we combined the CT and CC genotypes for additional analysis. Under this dominant genetic model, the combined -460 CT/CC