Pharmacotherapy of Cancer PainA Practical Guide

Chronic pain is experienced by approximately one-third of all cancer patients and as many as 70 to 90% of those with advanced disease.1 Although established pharmacotherapeutic strategies have been demonstrated to benefit most patients, undertreatment remains common.1 This unacceptable situation must be remedied; relief of cancer pain is an ethical imperative and it is incumbent upon clinicians to maximize the knowledge, skill, and diligence needed to attend to this task.2Analgesic pharmacotherapy is the mainstay approach in the management of cancer pain.3,4 Optimal therapy depends on an understanding of the clinical pharmacology of analgesic drugs and comprehensive assessment of the pain, medical condition, and psychosocial status of the patient. Through a process of repeated evaluations, therapy with opioid, nonopioid, and adjuvant analgesics is individualized to achieve and maintain a favorable balance between pain relief and adverse effects.An expert committee convened by the Cancer Unit of the World Health Organization has proposed a useful approach to drug selection for cancer pain, which has become known as the "analgesic ladder" (Fig. 1).3 When combined with appropriate dosing guidelines, this approach is capable of providing adequate relief to 70 to 90% of patients.5-9 Emphasizing that the intensity of pain, rather than its specific etiology, should be the prime consideration in analgesic selection, the approach advocates the following three basic steps:Step 1. Patients with mild to moderate cancer-related pain should be treated with a nonopioid analgesic, which should be combined with an adjuvant analgesic if a specific indication for one exists.Step 2. Patients who are relatively nontolerant and present with moderate to severe pain, or who tail to achieve adequate relief after a trial of a nonopioid analgesic, should be treated with a socalled "weak" opioid; this drug is typically combined with a nonopioid and may be coadministered with an adjuvant analgesic or other adjuvant drug, if there is an indication for one.Step 3. Patients who present with severe pain, or fail to achieve adequate relief following appropriate administration of drugs on the second rung of the analgesic ladder, should receive a so-called strong opioid, which may be combined with a nonopioid analgesic or an adjuvant drug as indicated.