Pharmacologic management of adult breakthrough cancer pain.

The generally accepted current definition of breakthrough cancer pain (BTCP) is as follows: “a transient exacerbation of pain that occurs either spontaneously, or in relation to a specific and predictable or unpredictable trigger, despite relatively stable and adequately controlled background pain.”1 Spontaneous pain is also referred to as idiopathic pain. Triggers are also referred to as incidents or incident pain. The triggers can be a volitional act (eg, walking), nonvolitional act (eg, coughing), or procedural act (eg, dressing change).2 End-ofdose failure refers to medication wearing off before the next regular analgesic dose is due and is no longer considered a subset of BTCP. The causes of BTCP include the cancer itself, cancer treatment side effects, and comorbidities. A recent systematic review found that 1 in 2 patients with cancer pain experience BTCP.3 There have been a number of attempts to develop assessment tools for BTCP. A recently developed and validated breakthrough pain assessment tool by Webber et al4 is available at CFPlus.* Breakthrough cancer pain contributes substantially to the suffering experienced by cancer patients,5-7 affecting patients’ quality of life. Patients often have problems with movement, which prompts avoidance and results in a number of associated complications including joint stiffness, muscle wasting, pressure sores, and constipation. Difficulty completing activities of daily living prompts reliance on family members and health agencies. Psychological complications include mood disturbances, problems with interpersonal relationships, and a general lack of enjoyment of life. Unfortunately, BTCP is not always adequately managed; the reasons for this include limited use of nonpharmacologic treatments (eg, heat, ice, distraction, imagery, massage, transcutaneous electrical nerve stimulation), patient fear of medication addiction and tolerance, and patient dissatisfaction with medication effectiveness and side effects. Other reasons that are related to the availability of newer management options include difficulty matching the appropriate medication with the particular type of BTCP, availability and cost of newer treatments, and the lack of familiarity with these new treatments among patients and health care providers. Management of BTCP includes treating the underlying cause of the pain, avoiding or treating factors that precipitate the pain, modifying the background drug regimen, and using appropriate adjuvants and breakthrough medications. This article will focus on the latter. Pain “crisis” will not be addressed in this article (it is best managed in the inpatient setting with intravenous medications). The pharmacologic options for management of BTCP have increased considerably in the past decade. The prime stimulus for these new products is the management of a particular subset of BTCP, which has a fast onset and short duration and is often intense. Most of these new options are fentanyl based owing to the highly lipophilic nature of fentanyl, allowing for transmucosal absorption (sublingual, buccal, intranasal). Fast-acting fentanyl products are commonly referred to as rapid-onset opioids (ROOs). In the United States, they are often called transmucosal immediate-release fentanyl drugs. In Canada most BTCP cases are managed with only the traditional short-acting opioids (SAOs) (ie, morphine, hydromorphone, and oxycodone). Currently, there are 2 new fentanyl citrate products (administered sublingually or buccally) that have been approved and are available in Canada.8,9 An off-label option used in some centres is injectable fentanyl and sufentanil, administered sublingually rather than by injection.