الفهرس 
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Abstract
Low tumor oxygenation, also known as hypoxia, constitutes a major concern for brain cancer patients, since it promotes cancer cell spreading (invasion) into the healthy brain tissue in order to evade this adverse microenvironment. Tumor invasion not only constitutes a major obstacle to surgery, radiotherapy, and chemotherapy, but it is also the main cause of death in brain cancer patients. Understanding how hypoxia triggers cancer cells to become invasive is paramount to developing novel and more effective therapies against this devastating disease.
The aim of the study was to evaluate serum levels of osteopontin (OPN) and erythropoietin (EPO) as hypoxia markers in brain cancer patients.
This study included 73 subjects divided into two main groups:
group I: 30 healthy subjects age and sex matched with the cancer group.
group II: 43 brain cancer patients were subdivided into:
Glioblastoma subgroup: composed of 23 brain cancer patients (18 glioblastoma and 5 brain metastasis)
Meningioma subgroup: composed of 20 Meningioma patients.
Our results showed that:
OPN was significantly increased in all Brain Cancer Patients either before or after radiotherapy when compared to their corresponding control values. Moreover, this biomarker significantly increased after radiotherapy treatment when compared to before treatment.
Comparison between Meningioma and Glioblastoma subgroups according to serum OPN revealed that serum OPN after radiotherapy treatment in glioblastoma patients was significantly higher than in meningioma. However, nonsignificant difference was found in serum OPN levels between the two subgroups before radiotherapy.
Regarding EPO, it was significantly increased in all Brain Cancer Patients either before or after radiotherapy when compared to their corresponding control values. Moreover, their serum levels were significantly decreased after radiotherapy treatment when compared to before treatment.
Comparison between Meningioma and Glioblastoma subgroups according to serum EPO showed that serum EPO after radiotherapy treatment in glioblastoma patients was nonsignificantly different from that in meningioma patients. Also nonsignificant difference was found in serum EPO between the two subgroups before radiotherapy.
6.2 Conclusion
Form this study, it could be concluded that:
Higher serum levels of OPN in BCPs either before or after treatment indicate that OSP is a marker of malignancy and has a role in tumor development and progression. Moreover, association of significant elevation of serum osteopontin with aggressive and hypoxic tumor such as glioblastoma indicaties that osteopontin may be a biomarker of hypoxia and radiation resistance.
Higher levels of serum EPO in BCPs indicate tumor and therapy-related anemia which decreases the oxygen-carrying capacity of the blood and lead to tissue hypoxia. In turn, hypoxia is a recognized feature of radioresistance, hypothesize that elevated endogenous erythropoietin levels could be used as hypoxia biomarker, increase the aggressiveness of the disease and potentially impair treatment outcomes.