Low-dose methadone added to another opioid for cancer pain: a multicentre prospective study.

Treillet E, Perceau-Chambard E, Economos G, Chevalier L, Picard S, Frasca M, Pouget J, Calvel L, Tremellat-Faliere F, Majerus M, Quesnel PA, Chiquet R, Evin A, Seveque MA, Lebel A, Hardouin I, Burnod A, Renard O, Bessodes P, Giet O, Serresse L.