Managing cancer pain poorly responsive to systemic opioid therapy.

Large surveys of populations with cancer pain indicate that as many as 90% of patients can attain adequate relief of pain using optimal, systemic, opioid-based pharmacotherapy. Skilled clinicians should be able to achieve this benchmark and should also be knowledgeable about the variety of clinical strategies that may be used to manage pain in those patients who are poorly responsive to routine measures. These strategies can be conceptualized in four broad categories: 1) opening the "therapeutic window" by more aggressive side effect management, 2) identifying an opioid with a more favorable balance between analgesia and side effects through "opioid rotation," 3) introducing a pharmacologic technique that reduces the systemic opioid requirement (either treatment with a systemic coanalgesic or a trial of intraspinal therapy), or 4) offering a trial of a nonpharmacologic intervention that may reduce the systemic opioid requirement (e.g., nerve block). In the absence of comparative trials, the selection of a specific approach depends on an informed risk/benefit evaluation based on information from a comprehensive clinical assessment.