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Treating Breakthrough Cancer Pain Requires Recognition, Matching Drug to Goal

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ANAHEIM—Effective management of breakthrough cancer pain requires optimizing background therapy for chronic pain and accurately assessing the type of breakthrough pain, said presenters at the 45th American Society of Health-System Pharmacists Midyear Clinical Meeting & Exposition.

“Knowing the type of breakthrough cancer pain can help match the right drug with the right goal,” said Mary Lynn McPherson, PharmD, BCPS, CDE, who is professor and vice chair, Department of Pharmacy Practice and Science, University of Maryland School of Pharmacy in Baltimore. Newer rapidonset opioids are becoming the standard of management but opioids are often suboptimal when used alone.

The prevalence of breakthrough cancer pain varies, with estimates ranging from 30% to 90%, said Steven D. Passik, PhD. The pathophysiology is complex, with simultaneous nociceptive and neuropathic pain processes occurring, he said.

Older cancer patients may need to be probed for cancer pain because they often underreport their pain or will indicate that it’s controlled when it may not be, said Passik, who is associate attending psychologist, Department of Psychiatry and Behavioral Sciences, Memorial Sloan-Kettering Cancer Center in New York City.

Breakthrough cancer pain has been described as spikes of pain that occur on top of baseline well-controlled pain. Breakthrough pain typically has an onset of less than 3 minutes, occurs 1 to 4 times daily, and has an average duration of 30 minutes.

A combination of symptom assessment tools, patient history, and a physical examination to assess pain should be used to devise the treatment plan, said Passik. “Cancer pain patients are morphing into chronic pain patients,” he said. “You have to plan their opioid therapy in the same way as noncancer chronic pain patients.”

Unfortunately, no tools specific for breakthrough cancer pain are validated fully for routine clinical use. Pain is but one item among many contained in general cancer symptom scales, but scales such as The M. D. Anderson Symptom Inventory, the Edmonton Symptom Assessment Scale, and the Memorial Symptom Assessment Scale can help put pain into the context of other symptoms.

Key elements of the history include illnesses relevant to opioid therapy (ie, respiratory, hepatic, renal disease), medical illnesses suggestive of substance abuse (ie, hepatitis, HIV/AIDS, sexually transmitted diseases, liver disease, tuberculosis), and a history of substance abuse including alcohol, tobacco, and prescription drugs. “Cancer doesn’t protect a patient from having an addiction,” and patients with a history of addiction are not candidates for rapid-onset opioids, he said. Smokers have a higher rate of opioid abuse than nonsmokers, he added.

The Mental Health Inventory-5 can be used as part of the psychiatric history, and a score of less than 52 should trigger a formal evaluation.

Urine screens to monitor compliance and possible diversion of opioids are useful even in cancer pain management, he said. The Current Opioid Misuse Measure is a 17-item tool to address ongoing medication misuse but because this tool “overidentifies” misuse and abuse, it should only be used to identify potential cases for follow-up.

In the treatment of breakthrough cancer pain, controlling baseline persistent pain is paramount before moving forward, said McPherson.

“The patients are in the driver’s seat, and we need to control their pain to their satisfaction,” she said. For some patients, this may mean that achieving a numerical rating scale pain score of 3 or 4 (on a 0 to 10 scale) is satisfactory to allow them to interact with their families, whereas in others it may be inadequate.

One challenge in selecting the right drug is that the preferred option may not be possible because of cost and reimbursement barriers, problems with tolerability, and certain disease- or cancer therapy–related barriers, such as dysphagia, mucositis, and nausea.

The preferred pharmacologic agent to treat breakthrough pain will have pharmacokinetics that match the characteristics of the pain, she said. For pain brought on by predictable incidents, short-acting opioids with slower onset than fentanyl products can be used. Volitional pain, such as with wound care, should be premedicated.

For idiopathic or spontaneous pain with intense and/or fast onset, such as unpredictable pain upon awakening, rapid-onset opioids are a good option.

For end-of-dose pain, background therapy should first be optimized. Instead of more frequent administration of the dose, “stick with the dosage interval that’s approved and increase the dose,” advised McPherson.

She recommends using the Alberta Breakthrough Pain Assessment Tool, a research tool, to educate patients about breakthrough cancer pain. After understanding the difference between pain types, patients should be encouraged to distinguish chronic pain from breakthrough cancer pain in pain diaries.

Alternatively, 3 questions should be incorporated into the assessment:

  • Do you have pain flare-ups?
  • Are they predictable? If so, what are the causes?
  • How often do you have them?

Addressing the cause of pain can be as simple as prescribing antitussive medication for cough that triggers pain and avoiding invasive procedures when they won’t change patient management.

After selecting a therapy, counsel patients to preempt pain when they recognize a prodrome.

In selecting the dose for a short-acting opioid for breakthrough, 10% to 15% of the daily background medication dose is a standard rule. When using rapid-onset opioids, always start at the lowest dose, even if switching from one fentanyl to another. Ensure that patients are opioid-tolerant before starting a rapid-onset agent: “You cannot start a transdermal fentanyl patch unless someone is opioidtolerant,” she said.

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