Physiological properties of malignant tumours.

It is generally accepted that tumour microcirculation, blood flow, oxygen and nutrient supply, tissue pH distribution, and the bioenergetic status--factors which are usually closely linked and which define the so-called metabolic microenvironment--can markedly influence the therapeutic response of malignant tumours to conventional irradiation, chemotherapy, other non-surgical treatment modalities, and the cell proliferation activity within the tumours. Currently available information on the parameters defining the metabolic micromilieu in human tumours is presented in this paper. According to these data, significant variations in these relevant factors are likely to occur between different locations within a tumour, and between tumours of the same grading and clinical staging. Therefore, evaluation of the metabolic microenvironment in individual tumours before therapy and a corresponding 'fine-tuning' of treatment protocols for individual patients may result in an improved tumour response to treatment.