Does tumour related oedema contribute to the hypoxic fraction of human brain tumours?

Focal hypoxia has been demonstrated and is known to contribute to the resistance of malignant brain tumours to radiation and chemotherapy. Using dynamic needle micro-polarography and tissue morphometry on biopsy specimens, the relationship between the effect of oedema on tissue structure and tissue pO2 was investigated in 24 patients undergoing craniotomy for tumour decompression. An inverse correlation (r = -0.84) was found for intercapillary distance and pO2 levels in peritumoural white matter, but this was less marked (r = -0.22) in tumour, probably as a result of sampling difficulties from tissue heterogeneity. Comparison of maximum pO2 levels in oedematous peritumoural white matter with those in tumour suggests that peritumoural oedema is unlikely to contribute to tumour hypoxia.