Abstract
Hypoxia-induced radiation resistance has been proposed to be a consequence of low vascular density in tumours. The purpose of the study reported here was to investigate possible relationships between pretreatment oxygen tension (pO2) and vascular density in patients with cervix carcinoma. Tumour pO2 was measured by the use of polarographic needle electrodes. Biopsies were taken from the electrode tracks and vascular density and tissue composition, i.e. volume fraction of carcinoma tissue, stroma and necrosis, were determined by stereological analysis. The vascular density of individual biopsies was related to the median pO2 of the corresponding electrode track. Tumour regions with vascular density below 24 mm mm(-3) always showed low pO2, whereas tumour areas with vascular density above 24 mm mm(-3) could show a high or a low pO2. This indicates the existence of a threshold value of about 24 mm mm(-3) for vascular density in cervix carcinoma; a vascular density above this value is probably needed before high pO2 can occur. Low vascular density might, therefore, be a useful predictor of hypoxia-induced radiation resistance in cervix carcinoma. High vascular density, on the other hand, can probably not be used to exclude radiation resistance. The differences in pO2 among tumour regions with high vascular density were not a consequence of differences in the amount of necrosis or stroma or in the haemoglobin concentration in peripheral blood of the patients. Model calculations indicated that these differences in pO2 could be explained by differences in the oxygen delivery alone and by differences in the oxygen consumption rate alone.