Chronic pain following treatment for cancer: the role of opioids.

Opioids are the most effective analgesics for severe pain and the mainstay of acute and terminal cancer pain treatments. In those settings, opioids are used over a limited time period so that opioid tolerance, if it develops, is relatively easy to overcome, and other problems of opioid use, including substance abuse, are unlikely to be problematic. As cancer treatments improve and increasing numbers of cancer patients experience long remissions, chronic pain due to cancer, or to cancer treatment, becomes a clinical problem that oncologists will encounter. Chronic pain differs from acute and terminal pain in several fundamental respects. In the case of chronic pain, functional restoration is a predominant goal of treatment. Because it is often due to neuronal damage, the pain may be particularly sensitive to nonopioid medications, and opioids can be reserved for refractory pain. If opioids are chosen, tolerance, dependence, and addiction can interfere, and safeguards designed to minimize these must be built into the treatment plan. This article reviews the principles of chronic opioid therapy for non-cancer pain and how these principles may be adapted for patients with chronic pain due to cancer.