Abstract
BackgroundThe tumor-associated glycoprotein osteopontin (OPN) is discussed as a plasma surrogate marker of tumor hypoxia and as an indicator of the presence of pleural mesothelioma in asbestos-exposed individuals. The clinical introduction of plasma OPN measurements requires the availability of a reliable enzyme-linked immunosorbence assay (ELISA).MethodsWe compared previously described and currently available ELISA systems on 88 archival plasma samples obtained from patients with head and neck or cervix cancer between 20 days before and 171 after the start of radiotherapy.ResultsMedian (range) plasma OPN levels were 667 (148.8–2095) ng/ml and 9.8 (3.5–189.5) ng/ml for a previously described and a newly marketed assay, respectively. Although results for different assays were significantly correlated (r = 0.38, p < 0.05, Spearman rank test), between-assay factors ranged from 2.0 to 217.9 (median 74.6) in individual patients. OPN levels in cervix cancer patients were comparable to those of head and neck cancer patients.ConclusionCommercially available OPN ELISA systems produce different absolute plasma OPN levels, compromising a comparison of individual patient data with published results. However, different assays appear to have a similar capacity to rank patients according to plasma OPN level. A review of literature data suggests that plasma OPN levels measured even with identical ELISA systems can only be compared with caution.
Highlights
The tumor-associated glycoprotein osteopontin (OPN) is discussed as a plasma surrogate marker of tumor hypoxia and as an indicator of the presence of pleural mesothelioma in asbestos-exposed individuals
It is currently unclear whether OPN may be useful to predict tumor hypoxia in other entities in which oxygenation has prognostic impact such as cervix cancer [3,4]
The time points at which samples were taken were not necessarily comparable between cervix and head and neck cancer patients, both assays indicated similar plasma OPN levels in these two tumor entities with
Summary
The tumor-associated glycoprotein osteopontin (OPN) is discussed as a plasma surrogate marker of tumor hypoxia and as an indicator of the presence of pleural mesothelioma in asbestos-exposed individuals. Recent publications have renewed interest in the measurement of OPN, a tumor-associated glycoprotein secreted into bodily fluids, in the plasma of tumor patients. OPN may serve as a marker by which to select head and neck cancer patients for intensified, hypoxia-specific, treatment. It is currently unclear whether OPN may be useful to predict tumor hypoxia in other entities in which oxygenation has prognostic impact such as cervix cancer [3,4]. Additional interest in OPN was raised by a prominent publication showing that in individuals with asbestos exposure, serum OPN levels can distinguish between those without cancer and those with pleural mesothelioma [5]. A molecular mechanism for the intracellular accumulation of OPN under hypoxia has recently been described [6,7], secretion of OPN may require additional steps [8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
