VEGF and sVEGFR-1 in malignant pleural effusions: association with survival and pleurodesis outcomes.

VEGF is a key mediator of tumour growth and metastasis and is considered central to the formation of exudative pleural effusions. This study examined the relationship between levels of VEGF and its soluble receptor, sVEGFR-1 in the pleural fluid and plasma of patients with malignant pleural effusions and their association with pleurodesis outcomes and survival. 103 patients with malignant pleural effusions were recruited at their first presentation. Follow-up was to 6 months or death. Survival and pleurodesis outcomes were robustly ascertained. VEGF and sVEGFR-1 were measured in pleural fluid and plasma by ELISA. VEGF and sVEGFR-1 were present in significantly higher concentrations in pleural fluid than plasma. There was no significant correlation between mediators within or between sample types. There was no association between baseline pleural fluid VEGF or sVEGFR-1 levels and pleurodesis failure. In both sample types, survival was inversely associated with sVEGFR-1 and within the non-small cell lung cancer sub-group (n=26), a highly significant association between increased pleural fluid VEGF and sVEGFR-1 and reduced survival was demonstrated (p=0.02 and 0.004 respectively). In conclusion, we have shown for the first time that sVEGFR-1 can be reproducibly measured in pleural fluid from malignant effusions. High levels at presentation in those with non-small cell carcinoma are strongly associated with poor outcomes.