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Prognostic significance of placenta growth factor expression in patients with multiple cancers: a meta-analysis.

BACKGROUND
Placenta growth factor (PLGF) is a member of the vascular endothelial growth factor (VEGF) family which is associated with the progression and metastasis of cancer. However, whether it can be used to predict prognosis in multiple cancer is still inconsistent.


METHODS
A meta-analysis was performed by searching electronic databases updated to December 2014. Eligible studies which evaluated the relationship between PLGF expression level and survival of patients with multiple cancers were conducted. Overall survival (OS), progression-free survival (PFS), hazard ratio (HR), and 95% confidence intervals (CI) were calculated.


RESULTS
Nineteen studies with a variety of cancers were included for the meta-analysis. Combined HR suggested that high expression of PLGF significantly associated with a poor OS (HR=1.69, 95% CI, 1.32-2.16), and PFS (HR=1.8, 95% CI, 1.33-2.44) in patients with different cancers. Moreover, a subgroup analysis based on cancer type demonstrated that high expression level of PLGF predict poor OS in both digestive system carcinoma (HR=1.63, 95% CI, 1.21-2.19; I(2)=80.7%, P<0.001) and respiratory system tumor (HR=1.75, 95% CI, 1.28-2.41; I(2)=0.0%, P=0.394). For PFS, the similar result was found in respiratory system tumor (HR=1.64, 95% CI, 1.23-2.19; I(2)=0.0%, P=0.807), but not in digestive system carcinoma (HR=1.81, 95% CI, 0.93-3.52; I(2)=80.2%, P<0.001).


CONCLUSION
Our meta-analysis demonstrates that PLGF might be regarded as a poor prognostic fact for multiple cancers. More large-scale and well-designed studies are still needed to strengthen our findings.