From "Breakthrough" to "Episodic" Cancer Pain? A European Association for Palliative Care Research Network Expert Delphi Survey Toward a Common Terminology and Classification of Transient Cancer Pain Exacerbations

Context: Cancer pain can appear with spikes of higher intensity. Breakthrough cancer pain (BTCP) is the most common term for the transient exacerbations of pain, but the ability of the nomenclature to capture relevant pain variations and give treatment guidance is questionable. Objectives: To reach consensus on definitions, terminology, and subclassification of transient cancer pain exacerbations. Methods: The most frequent authors on BTCP literature were identified using the same search strategy as in a systematic review and invited to participate in a two-round Delphi survey. Topics with a low degree of consensus on BTCP classification were refined into 20 statements. The participants rated their degree of agreement with the statements on a numeric rating scale (0-10). Consensus was defined as a median numeric rating scale score of ≥7 and an interquartile range of ≤3. Results: Fifty-two authors had published three or more articles on BTCP over the past 10 years. Twenty-seven responded in the first round and 24 in the second round. Consensus was reached for 13 of 20 statements. Transient cancer pain exacerbations can occur without background pain, when background pain is uncontrolled, and regardless of opioid treatment. There exist cancer pain exacerbations other than BTCP, and the phenomenon could be named "episodic pain." Patient-reported treatment satisfaction is important with respect to assessment. Subclassification according to pain pathophysiology can provide treatment guidance. Conclusion: Significant transient cancer pain exacerbations include more than just BTCP. Patient input and pain classification are important factors for tailoring treatment.