1. Department of Surgery, Pain Therapy and Rehabilitation Unit, Milan, Italy
2. Department of Biostatistics, Pain Therapy and Rehabilitation Unit, Milan, Italy
3. Palliative Care, Pain Therapy and Rehabilitation Unit, Milan, Italy
4. European Palliative Care Research Centre, Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
5. Department of Cancer Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy