(ChemotherapyAdvisor) – Elevated expression of vascular endothelial growth factor (VEGF) is associated with poor survival times, according to a meta-analysis published online in the journal Gynecologic Oncology.

Despite inter-study variation in measurement methodologies and cut-off levels for VEGF expression, the new meta-analysis of data pooled from 16 studies found that overall, “overexpression of VEGF in both primary tumor and serum is prognostic of progression-free (PFS) and overall survival (OS) in ovarian cancer,” reported lead author Lei Yu, MD, of the Ultrasonics/Gynecological Oncology Laboratory at the West China Second University Hospital at Sichuan University, in Chengdu, China, and coauthors.

However, the association between high tissue VEGF levels and poor prognosis “exists in early-stage patients, but not in advanced-stage patients,” they cautioned.

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The prognostic importance of VEGF expression in ovarian cancer has been “inconclusive,” the authors noted, with inconsistent results from numerous studies. The authors therefore pooled data from 16 English- and Chinese-language studies (representing a total of 1,111 patients) to determine overall associations between VEGF expression and survival rates among patients with ovarian cancer.

Elevated serum VEGF levels were significantly correlated with shorter PFS (HR 2.46; 95% CI, 1.84-3.29) and OS (HR 2.21; 95% CI, 1.57-3.13), the meta-analysis revealed. Elevated tumor tissue VEGF levels were also associated with PFS (HR 1.63; 95% CI, 1.09-2.42) and OS (HR 1.70; 95% CI, 1.01-2.87).

However, serum VEGF levels appeared to be “of more prognostic value than the (tumor) tissue value, as demonstrated by the larger hazard ratio and reduced heterogeneity” between studies, the authors pointed out. Variability of imnmunohistochemical methodologies for measuring VEGF were also a source of inter-study heterogeneity, they cautioned. Different studies also employed differing cut-off values for VEGF serum levels. These boundary values, used to define high and low expression levels, “should be standardized,” the authors emphasized.

The authors excluded from the meta-analysis, data from studies with fewer than 20 participants and studies that reported only non-VEGF-A levels or VEGF gene polymorphisms (without reporting VEGF protein levels).