In recent years, there has been great interest in exploiting the hypoxic tumour microenvironment for therapeutic gain. It has also become clear that this microenvironment is acidic and thus hostile to the growth and survival of viable normal cells. These observations lead to several fundamentally important questions that form the basis for this book. What are the relationships between tumour perfusion and tumour pH? What are the effects of tumour pH and hypoxia on carcinogenesis or tumorigenesis? What are the therapeutic consequences of tumour pH? This exciting book brings together leading clinicians and researchers to address some of these key issues. It is hypothesized that low extracellular pH is not only an important consequence of tumour growth but may also promote further tumorigenic transformation. Furthermore, in vitro studies suggest that low pH strongly affects the efficacy of chemo- and radiotherapy. Therapeutic strategies taking into account the consequences of altered pH, or which seek to manipulate tumour pH, more be more effective than those currently employed.