The role of vascular endothelial growth factor in the survival of patients with lung cancer: a systematic literature review and meta-analysis

The process of angiogenesis is an important factor in tumour development. One of the principal factors implicated in this process is vascular endothelial growth factor (VEGF) which induces, among other things, an increase in vascular permeability. We have undertaken a systematic review of the English and French literature in order to clarify its effect on the survival of patients with small cell (SCLC) and non-small cell (NSCLC) lung cancer To be eligible studies had to deal with the the evaluation of VEGF or its receptors in lung cancer and describe the relationship of their expression to survival. The survival figures were subject to meta-analysis after a methodological evaluation by means of a specific numerical scale evaluating the design of the study, the methodology (including laboratory techniques), and the analysis of results. Among the 20 studies selected 15 identified VEGF expression, using univariate analysis, as a statistically significant indicator of poor prognosis. 17 reported sufficient data to allow aggregation of the survival figures, of which 15 were devoted to NSCLC,(1,54.9 patients). The median overall methodological score was 48.3% (range 21.8-72.4%), without significant difference (p = 0.63) between studies eligible or non-eligible for meta-analysis. The meta-analysis, using the authors' threshold of. positivity for VEGF showed that VEGF is an unfavourable prognostic factor in NSCLC (HR = 1.48; 95% confidence interval 1.27-1.72). The data were insufficient to determine the prognostic value of VEGF in SCLC and that of its two receptors Flt-1 and KDR, with 1, 2 and I published studies respectively. In conclusion the expression of VEGF in MSCLC is a factor indicating a poor prognosis.