Contribution of Radiation Oncology to Cancer Cure and Palliation. Chapter 2

Over the past 30 years, computed tomography and magnetic resonance imaging have made possible the three dimensional (3-D) visualization of gross tumour volume as well as organs at risk, enabling 3-D treatment planning and conformal therapy techniques. These techniques form the backbone of a large number of prospective, randomized clinical trials exploring radiation dose escalation, altered fractionation (in particular hypofractionation) and/or the addition of a variety of systemic agents. These trials constitute the basis of much of the contemporary practice of evidence based radiation oncology even today. Some illustrative examples are summarized below. More recently, for many kinds of cancers the use of FDG-PET (fluorine-18 fluorodeoxyglucose positron emission tomography) for staging has improved patient selection by identifying patients with distant metastases for whom 'curative' radiotherapy would be futile. During the past decade, intensity modulated radiation therapy (IMRT), stereotactic radiotherapy, proton radiotherapy and carbon ion radiotherapy have attracted a great deal of publicity and resources, but their evidence base remains weak at present. They have not been proven to prolong the survival of cancer patients over standard 3-D conformal techniques. Furthermore, implementing adequate quality assurance measures for these techniques has proven difficult not only in less developed countries, but even in some more developed countries such as the United States of America. This chapter describes selected radiation oncology studies that have had a significant impact in the routine treatment of common adult cancers with radiotherapy. The authors have selected studies which in their opinion have changed or have the potential to change the practice of radiation oncology and improve the outcomes for cancer patients, both for cure and for effective palliation.