1 Supportive/Palliative Care Unit, La Maddalena Cancer Center, Palermo, Italy. Electronic address: terapiadeldolore@lamaddalenanet.it.
2 Department of Biotechnological and Applied Clinical Sciences, Section of Clinical Epidemiology and Environmental Medicine, University of L'Aquila, L'Aquila, Italy.
3 Anesthesiology and Pain Medicine, Department of Life Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy.
4 Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.