The Interactions of Polarographic Measurements of Oxygen Tension and Histological Grade in Human Glioma

Abstract

The purpose of this study is to investigate the implications of hypoxia and histological grade for survival in patients with gliomas. Tissue oxygen tension was measured intraoperatively using an Eppendorf pO2 Histograph. Survival was calculated from the date of the Eppendorf study to the date of last follow-up. Univariate analysis was performed stratifying patients by patient gender, type of anesthesia used, histological grade, extent of surgery, and patient age. Lastly univariate analysis was performed on the cohort after dichotomizing the median pO2 at 2.0 mmHg, 5.1 mmHg, and 10.0 mmHg. From March of 1996 to June of 1999, 25 patients were entered into this prospective trial. Two patients were excluded from analysis because polarographic measurements included normal brain tissue as well as tumor. Thus for analysis we included 13 patients with high grade gliomas (HGG) and 10 with low grade gliomas (LGG). The median tumor oxygen pressure for the entire cohort was 5.1 mmHg. Higher grade (P=0.0012) was prognostic for poorer survival. Patients were then stratified into groups with a median tumor oxygen tensions either above or below 2.0 mmHg, 5.1 mmHg, and 10.0 mmHg; there was no significant difference found in overall survival. Although histological grade was prognostic for survival, hypoxia, represented as the median tumor oxygen tension, was not a significant independent prognostic indicator of survival in this small and heterogeneous series of patients.