There is a great deal of interest in the effective use of opioids for cancer pain due to concerns from both clinicians and patients about addiction. When used correctly, opioids are capable of relieving pain in more than 90 percent of cancer patients. In reality, patients world-wide continue to endure pain usually due to irrational fears about using them. Fear of addiction is fed by outdated knowledge about opioids and the unintended effects of the war on drugs. However, new research shows that using opioids appropriately for pain management is effective, safe, and has an extremely low potential to produce addiction. This book provides evidence (on which guidelines can be based) from an international group of editors and contributors on opioids in cancer pain management, aimed at palliative care doctors, pharmacists, pain specialists, and oncologists. It includes information on opioid pharmacokinetics as a basis for understanding opioid analgesia, dosing schedule, polymorphisms of analgesic receptors in relationship to tolerance, and intrinsic efficacy. The main body of the book covers individual opioids. Topics within each chapter include structure, pharmacokinetics, pharmacodynamics, routes of administration, toxicity, drug interactions and influences of dosing and kinetics related to organ function. A chapter is dedicated to the WHO analgesic guidelines and opioid choices.