16 - Opioids in Cancer Pain

Summary

Introduction

Opioids are the most effective treatment in patients with cancer pain (Health and Welfare, Canada, 1984; Foley, 1985). The general principles of pharmacology that are described elsewhere apply also to cancer patients. However, pain syndromes in cancer are unique in intensity and duration, so that opioids must be used at the highest doses in clinical medicine. In addition, cancer patients present with a number of devastating symptoms that require specific treatment, including nausea, delirium, asthenia, and dyspnea. These symptoms and the drugs used in their treatment influence the pattern of opioid use.

This chapter discusses some of the unique characteristics of pain syndromes and clinical situations of cancer patients and their implications for opioid management of cancer pain.

Characteristics of Patients with Cancer Pain

Approximately 80% of cancer patients develop pain before death (Health and Welfare, Canada, 1984; Foley, 1985). Pain occurs more frequently in patients with locally advanced or metastatic cancer, and in approximately 80% of cases the pain is due to the presence of the tumor (Foley, 1985). However, almost one in five advanced cancer patients experience pain as a function of the treatment (radiotherapy or surgical fibrosis, chemotherapy-induced neuropathies), general weakness (tendon retraction, pressure ulcers), or unrelated conditions. Therefore, it is crucial to establish the cause of the pain even in patients with documented disseminated cancer.