This book summarizes current knowledge on blood perfusion and the microenvironment of human tumors, enabling the reader to gain a deeper insight into the physiological components of malignant tumors. Among a range of topics, detailed consideration is given to circulatory parameters, including blood and nutrient supply, transvascular and interstitial transport, and oxygenation, as well as to bioenergetic status and the influence of pH on the responsiveness of malignant tumors to nonsurgical treatments such as radiotherapy and chemotherapy. For the clinician, it will be of special interest to read about the various invasive and noninvasive methods (including MR and PET) that allow the tumor physiology and microenvironment of an individual patient to be characterized.