Breakthrough pain: definition and management.

Breakthrough pains are highly prevalent but poorly characterized phenomena that may be experienced by the cancer patient. The term encompasses a diverse group of transient pains that vary in their relationship to the fixed analgesic dose, temporal characteristics, precipitating events, predictability, pathophysiology, and etiology. Successful management is usually possible using a combination of primary oncologic interventions, optimization of the fixed analgesic regimen, and one or more of a variety of analgesic modalities, the mainstay of which is pharmacotherapy with a so-called "rescue-dose."