Breakthrough cancer pain and current treatment options

Cancer patients with relatively stable chronic background pain may experience transient episodes of pain, known as breakthrough cancer pain (BTP). There is no universally accepted definition for BTP, although recent efforts have been made by the Association for Palliative Medicine of Great Britain and Ireland to refine existing definitions and diagnostic criteria. Common clinical features of a typical BTP episode include a rapid onset peaking within minutes, a severe intensity and a short duration. BTP affects patients' quality of life through functional impairment and affective disturbances, and may also impact on healthcare resources through increased visits to physicians, hospitalisations due to pain, etc. As such, effective treatment is critical. Oral opioids are the mainstay of treatment for BTP. However, these are slow-acting with characteristics that do not match those of a typical BTP episode, and have the potential for over-medication and side effects. More favourable options would include treatments with a rapid onset, such as recently developed formulations of fentanyl, e.g., oral transmucosal fentanyl citrate (OTFC), buccal fentanyl citrate (FBT), and sublingual fentanyl citrate (SLF). However, these all require saliva/moisture to dissolve, potentially causing administration problems for cancer patients who commonly suffer from a dry mouth. The recently developed intranasal formulation of fentanyl (intranasal fentanyl spray) has a rapid onset and overcomes oral difficulties. It is a promising new option for the treatment of BTP.