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Occludin expression in brain tumors and its relevance to peritumoral edema and survival.

PURPOSE
Peritumoral brain edema (PTBE) is a serious causative factor that contributes the morbidity or mortality of brain tumors. The development of PTBE is influenced by many factors, including such tight junction proteins as occludin. We evaluated the PTBE volume and survival time with respect to the occludin expression in various pathological types of brain tumors.


MATERIALS AND METHODS
Fresh-frozen specimens from sixty patients who had brain tumors were obtained during surgery and the tumors were confirmed pathologically. The occludin expression was investigated by Western blot analysis. The PTBE volume was measured by using preoperative magnetic resonance (MR) imaging, and the survival time in each patient was estimated retrospectively.


RESULTS
Occludin was detected in 41 (68.3%) of the cases with brain tumors and it was not expressed in the other 19 (31.7%) cases. Although the lowest expression was revealed in high-grade gliomas, its expression was variable according to the pathology of the brain tumors (p>0.05). The difference of PTBE volume between occludin-positive and negative brain tumors was statistically significant (2072.46+/-328.73 mm(3) vs. 7452.42+/-1504.19 mm(3), respectively, p=0.002). The mean survival time was longer in the occludin-positive tumor group than in the occludin-negative group (38.63+/-1.57 months vs. 26.16+/-3.83 months, respectively; p=0.016).


CONCLUSIONS
This study suggests that the occludin expression is highly correlated to the development of PTBE in brain tumors and it might be a prognostic indicator for patient survival.