PERI-TUMORAL HYPOXIA IN HUMAN BRAIN - PEROPERATIVE MEASUREMENT OF THETISSUE OXYGEN-TENSION AROUND MALIGNANT BRAIN-TUMORS

Malignant brain tumours contain focal hypoxic areas that may increase their resistance to chemotherapy and radiotherapy. Following surgical excision, the peri-tumoural area will contain residual viable tumour c ells, and this area is therefore the logical site for subsequent thera py. The new bioreductive agents are metabolized under hypoxic conditio ns to produce a cytotoxic species. Peroperative peri-tumoural micro-po larographic measurments have been made to establish the oxygen environ ment of this region and to determine whether the hypoxic conditions mi ght allow for bioreductive drug activation. The micro-polarographic me thod is described and results are presented for ''normal'' white matte r (8 patients) to allow comparison with peri-tumoural brain (8 patient s) before and after removal of the tumour. The results suggest that pe ri-tumoural brain (median pO2 10.8 mmHg, 18% pO2 < 2.5 mmHg) is marked ly hypoxic in comparison with the ''normal'' brain (median pO2 15.3 mm Hg, less than 2% < 2.5 mmHg), and that surgery improves peri-tumoural oxygenation towards that of the ''normal'' white matter. It is conclud ed that the hypoxic peri-tumoural area can provide the conditions unde r which bioreductive agents may be activated.