Episodic (Breakthrough) Pain Prevalence in a Population of Cancer Pain Patients. Comparison of Clinical Diagnoses With the QUDEI-Italian Questionnaire for Intense Episodic Pain. - Caraceni A; Bertetto O; Labianca R; Maltoni M; Mercadante S; Varrassi G; Zaninetta G; Zucco F; Bagnasco M; Lanata L; De Conno F; Breakthrough/Episodic Pain Italian Study Group (Journal of Pain & Symptom Management, 2012)