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Relationship between tumor blood flow and serum albumin levels: A positron emission tomography study.

3058 Background: Positron emission tomography (PET) is increasingly used to aid development of drugs targeting the tumor vasculature. Reduced serum albumin levels lead to a decrease in plasma colloid osmotic pressure, reducing the effective intravascular volume. This study examined the relationship between serum albumin levels and tumor perfusion parameters evaluated with PET.


METHOD
PET perfusion studies using oxygen-15-labeled water (H215O) were performed as part of clinical trials in 18 patients with advanced solid tumors. Regional tumor blood flow (mlblood/min/mltissue) and volume of distribution of water (Vdwater;ml/mltissue), an indicator of the fraction of tissue participating in the exchange of water, were measured prior to any intervention and related to serum albumin levels. Two-tailed Pearson's correlation coefficient was used for statistical analysis.


RESULTS
Serum albumin levels ranged from 19 to 44g/l (median 32g/l). Regions of interest were drawn in 7 renal cell cancers, 5 liver metastases, 2 hepatomas, 2 para-aortic lymph node metastases, one mesenteric and one pelvic mass. Tumor blood flow ranged from 0.13 to 1.67mlblood/min/mltissue (median 0.47mlblood/min/mltissue) and tumor Vd water from 0.39 to 1.11ml/mltissue (median 0.69ml/mltissue). A significant correlation between serum albumin level and tumor blood flow (r=0.51, P=.031) could be demonstrated, whereas Vdwater was independent of albumin levels (r=0.29, P=.21).


CONCLUSIONS
This study demonstrates that tumour blood flow is related to serum albumin levels. Changes in serum albumin levels need to be considered when assessing effects on tumor blood flow with treatments targeting the tumor vasculature, particular if given over several weeks. The fraction of perfused tissue may more accurately assess the vascular effects of cancer treatments. If correction of serum albumin levels could be used for therapeutic benefit will require further research. No significant financial relationships to disclose.