Review of cancer pain management in patients receiving maintenance methadone therapy.

Methadone is commonly used in the treatment of heroin addiction. Patients with a history of opioid misuse or on methadone maintenance therapy (MMT) with cancer often have difficult to manage pain. We studied 12 patients referred to the palliative care service with cancer pain who were on MMT. All had difficult to control pain, and a third required 5 or more analgesic agents. Two patients had documented ''drug-seeking'' behavior. Methadone was used subcutaneously as an analgesic agent in 1 patient. We explore why patients on MMT have difficult to manage pain, the optimal management of their pain, and the increasing role of methadone as an analgesic agent in cancer pain.