Guan et al. BMC Cancer 2010, 10:431 http://www.biomedcentral.com/1471-2407/10/431 The strength of this study is that we included patients with stage IIIa and IIIb only, who received radiotherapy mostly in the range of 60-70 Gy with detailed OS data. However, there are several limitations. First, the study could not address the mechanism of how the VEGF poly- morphisms influence the survival outcomes of lung can- cer patients. Previous study demonstrated a good correlation between TC/CC genotypes of the VEGF -460 T > C polymorphism and increased serum VEGF levels in colorectal cancer patients [21]. An increased serum VEGF expression was also observed in ovarian cancer patients carrying -634 C allele [22]. We are collecting related data to determine if there is such correlation between the VEGF polymorphisms and the VEGF protein levels in NSCLC patients. Secondly, we only included three common functional, promoter VEGF SNPs, which is far from comprehensive. Indeed, the VEGF gene is highly polymorphic with at least 140 variants reported to date http://www.ncbi.nlm.nih.gov/SNP/. Some important functional SNPs may be missed or the observed associa- tion may result from genetic linkages with other untyped SNPs. Thirdly, our sample size is not big enough to allow evaluation of interactions between the studied poly- morphisms and dose of radiation therapy. For the same reason, there appeared a wide confidence interval in our stratified analyses by tumor stage and the significance was lost due to the reduced statistical power. Therefore, a complete investigation of tagging SNPs in larger sam- ples may be necessary in future studies. Conclusion In summary, we found that the VEGF -460 C allele may be associated with a better survival of LA-NSCLC patients treated with chemoradiotherapy. Future pro- spective studies with large sample sizes and better study designs are required to confirm our findings. Acknowledgements We thank Jiangong Niu, Jianzhong He and Kejing Xu and for their technical assistance. This study was in part supported by National Institutes of Health grants R01 ES11740 and R01 CA 131274 (to Q. W.) and P30 CA 16672 (to M. D. Anderson Cancer Center). Author details 1Department of Epidemiology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, Texas 77030, USA. 2Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, Texas 77030, USA. Authors’ contributions XXG, QYW, and ZXL designed the study. XXG, ZSL and XLY performed the experiments. XXG, MY, and HZ analyzed the data. XXG and MY wrote the manuscript. LEW, MSO, and RK coordinated the data and helped to revise the manuscript. All authors read and approved the final manuscript. Competing interests The authors declare that they have no competing interests. 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